With 95% of Bitcoin Now Mined, Can the Network Stay Secure After Block Rewards End?

Bitcoin quietly crossed a symbolic threshold on March 9: the circulating supply surpassed 20 million BTC. That means roughly 95% of the 21 million coins that will ever exist are now in circulation, leaving fewer than 1 million still to be mined over the next century.

For long-term holders, this cements Bitcoin’s scarcity story. For miners, it intensifies pressure on already thin margins. And for anyone concerned with the health of the network, it sharpens a question that can no longer be treated as distant theory: as block rewards dwindle, will there be enough economic incentive to keep Bitcoin secure?

The 20 Million BTC Milestone: What Actually Happened?

Bitcoin’s 20 millionth coin was mined at block height 940,000, according to data from Mempool. The block was mined by Foundry USA, one of the network’s largest industrial-scale mining pools.

It has taken roughly 17 years—from Bitcoin’s launch in 2009 to March 2026—to mine these first 20 million coins. The remaining sub-1 million BTC will dribble into circulation over more than a century, with the last satoshis expected around the year 2140. The schedule is not a guideline; it is encoded in Bitcoin’s protocol and has operated without interruption since launch.

That fixed cap and predictable schedule are central to how many in the industry frame Bitcoin’s role. Thomas Perfumo, chief economist at Kraken, contextualized the milestone in terms of scarcity, arguing that in contrast to fiat currencies with expandable supply, Bitcoin is “mathematically bound.” Simon Gerovich, founder of Japan-based Metaplanet, described the remaining 1 million BTC as the era when “true digital scarcity” begins.

Both Kraken and Metaplanet have significant financial exposure to Bitcoin—Kraken through trading revenues, Metaplanet via its treasury strategy—so their framing is not neutral. But the fact they are describing is independently verifiable: almost all of the eventual Bitcoin supply already exists, and the rate of new issuance is falling on a fixed schedule that no single government, company, or developer can unilaterally change.

How Bitcoin’s Halvings Are Squeezing Miners

Bitcoin’s issuance has always been front-loaded. When the network launched, miners earned 50 BTC per block. That subsidy has been slashed four times on a roughly four-year cadence:

• 2009–2012: 50 BTC per block
• 2012–2016: 25 BTC
• 2016–2020: 12.5 BTC
• 2020–April 2024: 6.25 BTC
• Since April 2024: 3.125 BTC

Each halving cuts the flow of new coins into the market. For holders, this underpins the scarcity thesis. For miners, the effect is more painful: revenue from new issuance is cut in half overnight, while operating costs—power, maintenance, staff, and capital expenditures—do not fall on the same schedule.

The strain is measurable. Hashprice—a metric that captures daily mining revenue per unit of computational power—fell below $30 per petahash per second per day in late February after a jump in network difficulty. Hashrate Index, which tracks this data, notes that around $30 sits at or below breakeven power cost for many operators, even before including broader corporate overhead.

Transaction fees are not yet picking up the slack. Over the week prior to the 20 million BTC milestone, miners earned on average about 0.0192 BTC in fees per block, according to Hashrate Index. Against a 3.125 BTC subsidy, fee income remains a small fraction of total miner revenue. That leaves miners overwhelmingly dependent on two variables they do not control: the block subsidy and Bitcoin’s market price.

Economic pressure is therefore not theoretical—it is visible in real-time profitability data. The protocol’s monetary policy is working exactly as designed; the question is how miners respond.

Miners Pivot to AI and New Revenue Streams

The tightening economics are accelerating a shift in how mining companies think about their business models. Broadly, two responses are emerging.

One group of miners is doubling down on Bitcoin. These firms are chasing higher efficiency, better hardware, cheaper power contracts, and larger scale as a way to survive thinner margins. In this model, success depends on being on the lower end of the global cost curve and on Bitcoin’s price remaining high enough to justify continued investment.

The other group is redefining what a “mining company” is. Instead of viewing their facilities purely as BTC production sites, they are repositioning them as energy and cooling infrastructure platforms. The same high-density data centers and power agreements used for Bitcoin mining can support more lucrative compute workloads, particularly artificial intelligence (AI) and other forms of high-performance computing.

Several publicly traded miners—such as Core Scientific, Bitfarms, TeraWulf, CleanSpark, and Hut 8—have announced AI- or HPC-focused pivots over the past year. Collectively, these companies have disclosed more than $43 billion in contracts tied to AI and high-performance computing services during this period.

From an investor’s standpoint, this diversification can look prudent: it reduces reliance on a single volatile asset and monetizes existing infrastructure in growth markets like AI. From the perspective of Bitcoin’s security model, however, there is a trade-off. Each megawatt devoted to AI rather than Bitcoin is hashrate that no longer contributes to securing the network.

The Fee Market vs. Security: A Debate Reaches Center Stage

The migration of well-capitalized miners toward AI hosting puts a long-running debate into sharper focus: can Bitcoin remain secure as the block subsidy approaches zero?

Bitcoin’s security model is straightforward in theory. Miners expend energy and compute to validate transactions and add blocks. In return, they earn newly issued coins (the subsidy) plus transaction fees. The more valuable and reliable that combined revenue stream is, the more incentive there is for miners to contribute hashrate. The more hashrate securing the network, the harder and costlier it becomes for an attacker to rewrite history or censor transactions.

Until now, the block subsidy has done most of the heavy lifting. The protocol assumes that, over time, fees will grow large enough to replace the subsidy as the primary incentive. But so far, evidence for that transition is limited: fee revenue is small relative to subsidy income, and halvings have widened the gap even as Bitcoin’s broader adoption and institutional interest have risen.

Concerns about this dynamic are not restricted to Bitcoin skeptics. Justin Drake of the Ethereum Foundation argued in 2025 that Bitcoin’s fee structure had not risen sufficiently to compensate for successive halvings and warned that persistently low fees could compromise long-term security. He characterized Bitcoin’s security model as “broken” and warned that a successful attack on Bitcoin could have systemic consequences for the broader crypto ecosystem.

Within Bitcoin circles, similar concerns are recognized in more measured terms. Developers and economists acknowledge the structural issue but generally counter with two assumptions:

• Price appreciation: If Bitcoin’s price continues to rise over time, the fiat value of a shrinking subsidy can still keep mining profitable, even as the BTC-denominated reward shrinks.
• Maturing fee market: As more users and institutions transact on Bitcoin and on layers built atop it—such as the Lightning Network and tokenization protocols—the volume and willingness to pay for block space will increase, making fee income a more meaningful portion of miner revenue.

Crucially, both assumptions are forward-looking and unproven at the scale required to fully replace the subsidy. Whether they hold will be determined over decades, not months.

What This Means for Bitcoin’s Next Decade

The 20 million BTC milestone offers a clear snapshot of where Bitcoin stands in this transition.

For investors, almost all of Bitcoin’s eventual supply is already in the market. The dilution rate is low and set to decline further on a schedule that cannot be easily altered. Combined with broader institutional adoption—through exchange-traded products, corporate treasuries, and professional capital allocations—this continues to underpin the “digital scarcity” investment narrative.

For miners, the same mechanics that support the scarcity thesis are compressing margins. Breakeven hashprice levels, modest fee income, and rising difficulty are forcing operational discipline and, in many cases, strategic reinvention. The emerging split between pure-play BTC miners and diversified compute providers is likely to deepen.

For the network’s security, the core question remains unresolved: can the combination of fee growth and price appreciation sustain enough hashrate to keep Bitcoin resilient once block rewards become negligible? If miners continue to divert capacity to AI and other workloads because they offer higher or more stable returns, Bitcoin’s security budget will increasingly depend on how much value the market is willing to pay, in fees, for each block of transactions.

None of this implies an imminent security crisis; the final coins will not be mined for more than a century. But the economic forces that will shape that future—shrinking subsidies, competitive energy markets, alternative compute demand, and evolving fee dynamics—are already visible today.

With 95% of all Bitcoin now mined, the protocol’s monetary policy is largely set in stone. What remains uncertain is how the human and economic systems built around it—miners, investors, and users—will adapt to keep the network secure long after the last satoshi enters circulation.