Who Really Controls Bitcoin? Inside the Centralization of Mining in 2025

Bitcoin once stood for something bold: a truly decentralized network where no single actor held the reins. It was a vision of shared power and open participation.

Now, that vision has dimmed.

With six mining pools responsible for more than 95% of block creation, Bitcoin’s decentralization is more fiction than fact. These dominant block template producers quietly dictate how the network runs.

They:

• Filter transactions before they ever reach a block,
• Control the network’s tempo with every template they push.

So far, Bitcoin transactions haven’t faced systematic censorship—though the cracks have shown. Functionally, the protocol still runs as designed.

But philosophically, something has changed. The myth of complete decentralization is harder to defend—not because anyone breached the system, but because power naturally gravitated toward a shrinking circle.

That’s the heart of the matter—the part we can’t ignore: how did we arrive at this extreme concentration of control, what are the consequences, and is there any way back?

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The Hidden Mechanics of Mining—and the Rise of Pool Power

To confront the issue of centralization, we first need to understand how mining really functions. Without that, the rest is just noise in the system.

• Why do only six pools hold such immense authority?
• How is work assigned and validated?
• And what power lies in shaping the block template?

What follows is a plain-language guide to why mining isn’t just a tech arms race—it’s also a vote on what the Bitcoin network becomes.

At its core, mining is the mechanism for adding new blocks. To win, miners must discover a unique cryptographic BTC fingerprint—called a hash—that proves the block is legitimate. The one who finds it first seals the block into history—and earns the prize.

Finding the right hash is nearly impossible alone—massive computing power dominates the field.

That’s why solo miners band together in mining pools, pooling their resources to compete with large-scale operations.

Mining pools operate as centralized coordinators within decentralized systems. They assign workloads to participants and handle reward distribution when a block is mined.

Importantly, the pool decides the contents of the block by assembling the template—selecting which transactions to include. The mathematical challenge is then passed to miners, who solve it without needing to interpret the block’s data.

So if it’s the pool that drafts the block, then it’s the pool that dictates the flow of value—choosing which transactions are admitted and which are discarded.

Miners? They’re the machinery. And the smaller the pool count, the narrower the pipeline of independent judgment that remains in the system.

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2025: Six Mining Pools Control 95% of Bitcoin Blocks

In 2025, the idea of Bitcoin as a decentralized system is increasingly hard to defend. Just six pools mine 95% of all blocks. They may appear autonomous, but the influence is anything but evenly spread.

The leading forces:

• Foundry holds about 30% of the network;
• AntPool and its proxy operations command slightly more than 30%;
• ViaBTC — 14.5%;
• F2Pool — 10%;
• MARA Pool — 5%;

All remaining pools? Together, they manage less than 10%.

This is where “proxy mining” becomes critical: it refers to a mining dynamic in which the block is mined under a smaller pool’s name, but the block template and job are distributed by a larger operator.

Such setups skew decentralization metrics—giving the impression of a distributed network while central command remains intact. This is the operational model behind “AntPool & friends”: affiliated pools working under AntPool’s direction, but listed independently.

To evaluate real-world centralization, the industry uses the Mining Centralization Index, which quantifies how much global hashrate is effectively managed by top-tier pools.

Bitcoin’s decentralization didn’t vanish overnight—it faded over time:

• Back in 2017, no more than 30% of hashrate was held by the top two pools; the top six held under 65%. A high point for decentralization.
• Between 2019 and 2022, the top two crept up to 35%, and the top six hovered around 75%.
• But by 2023–2025, the shift was dramatic: the top two now hold 60–70%, and the six largest pools control 96–99% of the network! 

Today, virtually every Bitcoin block is created under the oversight of one of these six players.

This isn’t about protocols anymore—it’s about corporations: entities with servers, supply chains, and shareholder interests.

The fewer the entities in control, the easier it becomes to influence transaction flow and policy.

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A 51% Attack Isn’t the Only Threat to Bitcoin

Talk of mining centralization often leads to the 51% attack—a takeover scenario where one actor controls over half the hashrate.

But Bitcoin’s biggest risks may not need a majority. Concentrated control alone can tip the balance.

The 51% attack might dominate headlines—but it’s not the most credible threat.

More likely than a brute-force assault is something slower: soft, systemic censorship. No exploits, just quiet exclusion.

Every Bitcoin block is a story built by someone. The block doesn’t write itself—it’s formed by the one who selects the plot: the block template. 

After constructing the block, the pool pulls in transactions from the mempool—Bitcoin’s backlog of pending transfers.

Here’s the key: it decides which to include. Selections can be made based on transaction fee, address type, metadata, or subjective criteria. Specific transactions can be excluded—intentionally or not.

Further reading: How Many Confirmations for Bitcoin Transactions and Why It Matters

The absence of overt censorship doesn’t ensure decentralization. Subtle forms of bias are already shaping Bitcoin’s infrastructure.

Mining pools, responding to economic and regulatory pressures, tend to:

• Prioritize low-complexity, high-fee transactions;
• Avoid addresses linked to legal risk in their operating regions;
• Adopt OFAC blacklists, actively filtering sanctioned entities from block templates.

One pool filtering transactions? Annoying, but manageable.

But if six of the top pools start moving in unison, we’re not talking about decentralization anymore—we’re looking at a slow, silent censorship mechanism.

And don’t let the 50% hashrate myth fool you. Even 40% gives a group a decent shot—around 50% probability—at building a six-block chain in a row, especially if the network is disrupted or the effort is well-planned.

There’s no attack on the network. And yet:

• Six mining pools forge 95% of all blocks;
• Meaning nearly every transaction passes through the same narrow lens;
• If outside pressure mounts, decisions can be fast—and one-sided.

This does not render Bitcoin dysfunctional. But it does make the system more fragile than many assume. Hashrate centralization is not a passive statistic—it’s a core vulnerability that challenges the network’s long-term neutrality and resilience.

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Ghash.io and the Day Bitcoin Faced Its Shadow

In 2014, Bitcoin stood at the edge of a cliff. Ghash.io, a dominant mining pool at the time, reached 42% of the network’s hashrate—close enough to 51% to trigger widespread panic.

Across Twitter (then Twitter), Reddit, and IRC, the community rallied. Miners fled. They understood the stakes.

One pool with majority power meant potential rollbacks, censorship, and double-spends. And the risk didn’t require 51%—even 40% gave Ghash a statistical edge to build six blocks ahead, threatening Bitcoin’s integrity.

Ghash.io, the mining arm of CEX.io, found itself in the eye of the storm. As its hashpower neared critical mass, accusations of irresponsibility flew fast.

The team swore it had no malicious intent—and tried to calm the community by:

• Halting new miner registrations,
• Limiting further growth,
• And promising to develop self-regulation policies. 

It wasn’t enough to restore trust, but it did slow the panic.

In that moment of tension, it was Vitalik Buterin—then a rising figure, now Ethereum’s co-founder—who gave voice to a deeper worry. He called for peer-to-peer mining, for tools anyone could use, so no one had to rely on giants.

The community listened. It resisted. For a while, the tide of centralization slowed. But the world has moved on. Mining today is steel, heat, and capital—and the kind of boycott that once worked may no longer stand a chance.

The Economics Behind Mining Centralization

The Bitcoin mining landscape has matured into a capital-intensive sector. It’s no longer about technical know-how—it’s about infrastructure and scale.

Modern mining demands:

• Purpose-built ASIC hardware;
• Megawatt-scale data centers;
• Low-cost energy contracts;
• Skilled engineering teams.

For retail miners, the barriers are insurmountable. Garage mining has given way to institutional operations, complete with financial modeling, strategic capital allocation, and operational risk management.

Mining centralization has accelerated, and it’s coming from two sides:

1. Hardware Hegemony

Companies like Bitmain don’t just sell the tools—they run the game. Their pool, AntPool, is a direct extension of their hardware empire, and the more ASICs they ship, the more control they accumulate.

2. Capital Concentration

Then there’s the money. Public mining giants now dominate infrastructure. Take Foundry—half of America’s large-scale miners route through it, giving it unprecedented leverage over the network’s pulse.

Bitcoin was architected as a decentralized, peer-to-peer protocol. Yet over time, mining has gravitated toward those with substantial capital reserves and political influence.

This isn’t the result of manipulation—it’s a reflection of economic scale and market forces.

However, as mining becomes increasingly industrialized, the concentration of control introduces systemic vulnerabilities. Fewer decision-makers mean greater risk to network resilience—and to the integrity of Bitcoin’s decentralized ethos.

Reflections: State Blockchain: Why Governments Launch Decentralized Registries

Can We Still Decentralize Bitcoin? The Tools Are Already on the Table

The centralization of Bitcoin mining isn’t a future risk—it’s happening right now. But that doesn’t mean we’re out of options.

Within the Bitcoin community, discussions around reversing the trend have been active for years. From protocol tweaks to infrastructure innovation, there’s no shortage of ideas aimed at bringing block production back into the hands of independent participants.

Alternatives? 

1. Solo Mining

In a market ruled by scale, solo mining may seem obsolete. But for those with the firepower, it’s a declaration: autonomy over optimization. No reliance on centralized actors like Foundry or AntPool—just raw hash and freedom.

2. User-Crafted Block Templates

Then there’s a different kind of rebellion. Not against pools, but against control. Ocean and DEMAND don’t just mine—they rewrite the rules. In their world, the miner chooses the transaction. The power to assemble a block shifts back to the edge, where it was always meant to be.

3. Home Mining Gains Ground

A new segment of the market is quietly expanding: small, low-noise ASIC devices such as the Antminer S9 Hydro and Bitaxe. While these units cannot rival industrial-scale data centers in terms of hashrate, their contribution lies in creating density and diversity across the network.

If thousands of independent nodes collectively generate even 1–2% of the global hashrate, that impact is measurable.

These initiatives are not silver bullets—they won’t instantly disrupt the dominance of the six largest mining pools. But they represent a strategic shift. Centralization didn’t happen overnight, and reversing it will take time. The trajectory, however, must be clear: the more participants who can mine independently, the stronger Bitcoin becomes.

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Can Bitcoin Truly Remain Decentralized?

At first glance, Bitcoin appears to be functioning flawlessly:

• Blocks continue to arrive roughly every ten minutes,
• The network remains online,
• Transactions are processed without interference,
• No single entity has seized control. 

But the real question isn’t whether Bitcoin runs—it’s who keeps it running.

We haven’t seen a collapse. But maybe that’s just because no one’s tried to break it. Yet.

Bitcoin’s technical defenses remain robust. But behind that resilience lies an architectural imbalance.

If the same actors build blocks, curate transactions, and dictate network behavior, control consolidates. Not through malice—but through quiet consensus.

Here’s what must be tracked:

• Who draws the block templates?
• Where does the hashrate flow?
• Are new pools rising—or swallowed whole?
• How much is left outside the dominant six?
• And can the people at the edges still touch the protocol?

Decentralization isn’t a checkbox you tick once and move on. In Bitcoin, it’s a living struggle—a daily push to prevent control from collapsing into too few hands.

Right now, everything’s quiet. But quiet isn’t the same as safe.

Especially when we’re talking about a $1.7 trillion market cap.