Only if 100% of everything is powered by renewables that could be a good argument (but see below), because there's always opportunity costs: The energy producti

Only if 100% of everything is powered by renewables that could be a good argument (but see below), because there's always opportunity costs: The energy production capacity used for crypto cannot be used for anything else, which means something else uses non-renewables now. Maybe an exception could be made if every crypto miner built their own renewable power source which provided all of the energy instead of relying on existing ones, but then the next point still stands: Renewable energy production has externalities, same as everything else. The power production equipment has to be built, which needs materials. It has to be transported, which needs energy. It needs to be maintained and so on. Just saying "well, we can always add a few more renewable power plants, who cares?" would only be valid if we could produce them out of thin air.