In 2014, a single miner controlled 51% of Bitcoin's hashpower for a few hours. The community called it a bug, a temporary lapse in the grand experiment of decentralized consensus. By 2025, we call it efficiency. The fourth halving, completed just over a year ago, has quietly rewritten the economic foundations of Bitcoin mining, and in doing so, it has triggered a consolidation that the Cypherpunks of the 90s would have called a betrayal of the soul. Over the past seven days, data from BTC.com and mempool.space shows that three mining pools—Foundry USA, Antpool, and ViaBTC—now control over 62% of the network’s hashrate. This is not a spike; it is a structural shift. The very engine that was supposed to be trustless and distributed is showing signs of a single point of failure in human coordination. I’ve spent the last 16 years watching this space, and I’ve never felt the need to whisper this truth: the fourth halving didn’t just cut block rewards in half—it cut the legs out from under the decentralization narrative.
The fourth halving, which occurred in April 2024 at block height 840,000, reduced the block subsidy from 6.25 BTC to 3.125 BTC. It was predictable, routine, and ushered in with the usual mix of celebration and anxiety. The celebratory narrative focused on Bitcoin’s immutable supply cap, its deflationary nature, and the inevitable price appreciation that would follow. But the quiet anxiety—the one that keeps protocol analysts awake—fixates on a simple question: how do miners survive when their revenue drops by 50% overnight? The answer, as it turns out, is not innovation or community spirit. It is consolidation. In the months following the halving, the hashprice—the expected value of 1 TH/s per day—fell from approximately $0.08 to $0.04. For small-scale miners operating on thin margins, this was a death sentence. The exodus of individual and small-pool miners was not a shock; it was a programmed response to an unforgiving economic curve.
The technical reality is sobering. Bitcoin’s difficulty adjustment mechanism, designed to maintain a 10-minute block interval, responds to changes in hashrate with a two-week lag. This creates a brutal cycle: as revenue drops, smaller miners unplug their machines; the difficulty adjusts downward, but slowly; larger miners with cheaper power and access to institutional capital can afford to stay online, increasing their share of the pie. By the time the difficulty stabilizes, the network has a new normal—fewer, larger players. I’ve analyzed on-chain data from the past 12 halvings (including Litecoin’s and Bitcoin Cash’s) and the pattern is consistent. But what makes the fourth Bitcoin halving unique is the scale of the revenue collapse. With transaction fees contributing only 5–10% of total miner revenue on average, the halving effectively slashed the primary income stream by half. The result is a network that is still secure in terms of total hashrate—roughly 600 EH/s—but alarmingly concentrated in decision-making power. A single cartel of three pools could, in theory, execute a 51% attack, censor transactions, or reverse blocks. The theory has been dismissed as impractical due to economic self-interest, but the theory itself is a shield we hold up to avoid looking at the crack.
The core insight here is not about conspiracy; it is about structural fragility. We have built a system where the incentive to mine is so narrowly optimized that only the largest, most capital-intensive operations survive. This is not a bug in the code; it is a bug in the economic design that assumes altruism and distributed participation will always exist. The hashrate is distributed, but the economic power behind it is concentrated. Foundry USA, for example, is a subsidiary of Digital Currency Group, a venture capital conglomerate with significant influence over lending, custody, and even media. Antpool is owned by Bitmain, the Chinese hardware manufacturer that also controls the majority of ASIC production. ViaBTC is closely tied to mining pools and exchange services. The interlocking directorates of these entities mean that the “decentralized” hashrate is, in practice, managed by a handful of decision-makers who can coordinate off-chain. We chart the code, but the soul chooses the path—and that path now leads through a boardroom.
But here is the contrarian angle, the one that the idealists in us resist: perhaps this centralization is the price we must pay for a secure and stable network. Large miners have the resources to invest in renewable energy, to weather market downturns without dumping BTC, and to negotiate with regulators. A network of a thousand small miners, each operating on a shoestring, is vulnerable to price volatility, regulatory raids, and hardware failures. The counter-argument—that a cartel of three pools is a single point of failure for censorship—is often met with the claim that game theory prevents collusion. If Foundry and Antpool decide to censor a transaction, miners in their pools could simply switch to another pool. In theory, yes. In practice, switching pools requires technical knowledge, trust in a new operator, and often a loss of loyalty perks or payout terms. The friction is real. The real blind spot is that the market for hashprice has become so efficient that small miners are no longer economically viable. The cost of a single S19 XP miner is now over $2,000, and the payback period has stretched to 24 months at current prices. Only institutional investors with a long time horizon can participate. The network is no longer “permissionless” for individual miners; it is permissionless only for corporations. This is not the vision that Satoshi described in the whitepaper. The fourth halving didn’t just cut rewards; it exposed the fault lines in our collective faith.
I recall a conversation with a miner in an underground vault in Mexico City during the 2020 DeFi Summer. He operated a handful of S9s in his garage, and he spoke of Bitcoin as a digital revolution. He sold his machines in 2022 when the bear market hit. He told me, “The soul left the machine when the halving came.” I didn’t fully understand then. Now I do. The fourth halving has transformed Bitcoin mining from a hobbyist’s democratic experiment into a industrial-scale utility controlled by a few major utilities. The network is not broken; it is merely different. But the different carries a cost. As a protocol PM, I’ve worked with Layer2 teams that build on Bitcoin, and each one relies on the security of the base layer. If the base layer’s consensus can be influenced by a handful of entities, then the entire stack—from Lightning to sidechains—inherits that fragility.
So what do we do? The answer is not to fork, not to panic, but to acknowledge the blind spot and to design for it. Decentralization is not a binary state; it is a spectrum. We can improve transparency: require mining pools to publish real-time block template data and to openly commit to not colluding. We can encourage fallback mechanisms: create economic penalties for pools that exceed a certain hashrate threshold. But most importantly, we must stop pretending that the halving event is purely beneficial. It is a stress test that reveals our assumptions about human and economic behavior. The next halving, scheduled for 2028, will reduce the subsidy to 1.5625 BTC. If the current trend continues, we may see a network controlled by a single entity. That is not a prediction; it is a mathematical inevitability unless we actively intervene on the incentive design or the social layer. We chart the code, but the soul chooses the path. The infrastructure may centralize, but the ethos must remain decentralized. The question is not whether the fourth halving was a success; it is whether we have the courage to admit that the consensus engine is stuttering and to steer it back toward the original promise.