Bitcoin’s network hashrate crossed 1 zettahash per second earlier this year - a threshold that felt theoretical not long ago - and the response from markets and media was something close to a shrug. That indifference is telling, and not in a way that flatters the people paying attention to price charts instead.

The April 2024 halving cut the block subsidy from 6.25 BTC to 3.125 BTC. The conventional expectation around halvings is miner capitulation: smaller, less efficient operations going offline as margins compress, hashrate dropping, difficulty adjusting downward. That did happen briefly in mid-2024. What followed, however, was a sustained expansion in mining capacity that has pushed difficulty to record levels through late 2025 and into 2026.

Who’s Still Building

The miners surviving - and expanding - post-halving aren’t running S19 Pros in converted warehouses. The operations scaling now are running next-generation ASICs, largely the Bitmain Antminer S21 series and MicroBT’s WhatsMiner M60 line, with energy efficiency below 20 joules per terahash. Location matters too: operations with access to sub-$0.03/kWh power - whether from stranded natural gas in the Permian Basin, hydro in Paraguay, or curtailed wind in West Texas - have a structural cost advantage that smaller miners simply cannot replicate.

This is a consolidation story as much as a growth story. The hashrate record doesn’t mean more participants; it likely means fewer, better-capitalised ones.

What Difficulty Means for Security

Higher difficulty translates directly to attack cost. A 51% attack on Bitcoin today would require sustained control of more than 500 exahashes per second - hardware and electricity expenditure that makes the economic case for such an attack essentially incoherent. That’s not a theoretical comfort; it’s the mechanism the network was designed around.

Transaction fees as a proportion of miner revenue remain too low for comfort in the long run, sitting well below 10% on most days. The block reward continues to carry mining economics. The next halving in 2028 will compress that further, and fee pressure is the unresolved question that record hashrate doesn’t answer.

But the network is more secure than it has ever been. That’s not nothing - it’s the foundation everything else is built on.