Short answer: mining can't stay unprofitable for the network as a whole. The difficulty adjustment ensures that.
The loop works like this:
Price falls, or the subsidy halves. The least efficient miners (old ASICs, expensive power) are now losing money per hash, so they switch off.
Hashrate drops, so blocks come slower than every 10 minutes.
At the next retarget (every 2016 blocks), difficulty drops roughly in proportion to the lost hashrate.
The miners who are still running now win a bigger share of each block, and they're profitable again.
So "unprofitable" always means unprofitable for the marginal miner. Miners with the cheapest energy (stranded gas, curtailed hydro, heat reuse, which is denlillaapan's point) keep going, and the rest leave until things balance.
Real example: the 2021 China ban knocked roughly half the hashrate offline. Blocks slowed for a couple of weeks, then the July 2021 retarget cut difficulty by about 28%, the largest drop on record. Nothing broke.
The weak spots people actually argue about:
The gap before a retarget. If price crashes just after an adjustment, slow blocks drag out the time until the next one. The adjustment is also capped at 4x per period. In practice that's an inconvenience, not a failure.
The long-run security budget. As the subsidy goes toward zero, fees have to pay for hashrate. The question isn't whether miners will be profitable (they will, at some hashrate); it's whether the equilibrium hashrate is high enough to make attacks uneconomic. That's the open debate.
On "tail emissions": that's Monero's answer to the security-budget problem. Bitcoin's design bets on fees instead, and changing that would need a hard fork, so it isn't something that happens automatically when mining gets tight.
tail emissions
nothing.
It's almost always been unprofitable. (charity or secondary uses like grid stabilization or heat reuse)
Short answer: mining can't stay unprofitable for the network as a whole. The difficulty adjustment ensures that.
The loop works like this:
So "unprofitable" always means unprofitable for the marginal miner. Miners with the cheapest energy (stranded gas, curtailed hydro, heat reuse, which is denlillaapan's point) keep going, and the rest leave until things balance.
Real example: the 2021 China ban knocked roughly half the hashrate offline. Blocks slowed for a couple of weeks, then the July 2021 retarget cut difficulty by about 28%, the largest drop on record. Nothing broke.
The weak spots people actually argue about:
On "tail emissions": that's Monero's answer to the security-budget problem. Bitcoin's design bets on fees instead, and changing that would need a hard fork, so it isn't something that happens automatically when mining gets tight.