Bitcoin’s mining difficulty adjusted upward again this week, continuing a trend that has pushed the metric to successive all-time highs through mid-2026. The hashrate - the aggregate computational power pointed at the network - has held above 800 exahashes per second for most of the year. By raw technical measures, the network has never been more secure.
The problem is who’s doing the securing.
The Economics Favor Scale, Brutally
Post-halving economics have compressed margins to the point where electricity cost is nearly the only variable that matters. The April 2024 halving cut the block subsidy to 3.125 BTC, and at current prices, a miner running older-generation ASICs - anything pre-S21 era - is likely operating at or below breakeven. The machines that were profitable in 2022 are now paperweights unless the operator has locked in sub-$0.03/kWh power, which essentially means either a large industrial deal or proximity to stranded energy in a handful of specific geographies.
Public miners like Marathon Digital and Riot Platforms have spent the last two years scaling aggressively and hedging power costs through long-term contracts. That infrastructure spending, which ran into the hundreds of millions for each company, is now the moat. A miner standing up a few hundred units in a rented colocation facility isn’t competing - they’re donating hashrate while waiting to be priced out.
Concentration Isn’t New, But It’s Accelerating
Mining pool concentration has been a recurring concern since at least 2014. What’s different now is that the concentration is happening at the hardware and energy procurement level, not just the pool level. Pools are somewhat cosmetic - a solo miner can point their rigs wherever they want. But if the underlying mining operations are owned by four or five publicly traded companies with institutional balance sheets, the decentralization argument becomes harder to sustain regardless of which pool processes the blocks.
One Data Point Worth Watching
The Cambridge Centre for Alternative Finance paused its Bitcoin Mining Map updates, which had been one of the few reliable public windows into geographic hashrate distribution. Without that, tracking how mining concentration evolves geographically is largely guesswork - which is its own kind of problem for anyone trying to assess the network’s actual resilience.
Difficulty records are real. Whether the decentralization that’s supposed to underpin them is equally real is a different question, and right now there’s less visibility into it than there was two years ago.