I'm all for allowing people to play with cryptocurrencies as a type of blockchain research, but just ban any bank/exchange from allowing conversions to actual hard currency. That allows research to continue, but it takes away the massive, greedy mining operations & almost all of the big waste associated waste. It also knocks out (mostly) the ransomware side; they can go back to demanding actual money again.
The US could do a much better job of addressing the issue rather than seemingly keeping a blind eye to it. A lot of exchanges support USD, so knocking that out would be a huge help to cutting out the waste.