Cryptucurrency is not bad for the environment what is bad is the miners that decide to mine the cryptocurrencies it is their choice if they want to use green energy or not and most of them at the moment are not using green energy and that is what the criticism comes from but I think because of the issues have not been highlighted slowly each miner will change to green energy.
they can be contented in their situation like they have a moderate fees for electricity thats why they dont bother switching to green energy and the transition to a different energy can also be complicated to some due to their area but for those that doesnt have a problem from switching to green energy why not ? they can be a big help in this issue .