If electricity was an unlimited non-polluting resource, sure. But when my neighborhood mining rig coal power plant gives me cancer, it's not just a simple marketplace thing.
then tax the electricity use (or, specifically, the fossil fuel use)?
(alternatively, tax the electricity use beyond a certain per-person allocation).
I agree that there can be harms from PoW, but this is because of the electricity use, and so the thing to tax is the electricity use. Rather than the state deciding what things it considers valid for an individual to value and seek, it should put the restrictions on the thing that more directly causes negative externalities to others.
If there is a concern that this would harm things that we are sufficiently convinced is objectively valuable (e.g. making it more costly than is appropriate for people to heat their homes), so that we want to not significantly impact the finances of people who are like, using "reasonable" amounts of electricity, then we can, as I said, put some threshold amount of electricity use per person below which there's no tax on it, and increase the tax rate above that amount to account for this (and use the revenue to pay for CO2 removal and/or green energy development).
Or, like, I suppose in the most extreme case you could (on e.g. an annual basis) give everyone an initial amount of CO2 credits and no one is allowed to emit CO2 beyond the credits they have (but unused credits can be bought and sold).
