Presumably if the price went down by a substantial chunk and stayed down for a while, the hashpower would also decrease, and so the difficulty would also decrease.

Also, if electricity prices went up, or if CO2 emissions were taxed, then hashpower would decrease, and the difficulty would go down in turn.

As for the rest... so what? It uses a lot of electricity and there is some pollution---but a lot of bitcoin mining is done with hydro or geothermal (and will be nuclear if bitcoin continues to grow), so, so what about some pollution?

So there's a simple question: how much value do we get out of this tech per CO2e it emits and per ton of e-waste it creates. And AFAICT the answer is: not enough to keep tolerating it in a time where humanity as a whole is seriously worried about climate change for the first time ever.

If you can magically move _all_ the miners to sites with excess renewable electricity and permanently slash the hash rate by 99.9% then maybe it can be tolerated. Until then I would welcome more China-style crackdowns on mining activity across the world.

If you aren't upset about this, you probably haven't studied it. I say that in a spirit of helpfulness. Fiat money grossly distorts all of humanity's economic output and therefore retards our progress on all things, including fixing climate problems. Just one example: The US is becoming a nation of renters because enormous funds are buying up the houses with fiat money they borrow nearly for free.

Fortunately, with bitcoin, we can do something about that, without (eventually) harming the environment.