Generally, cryptocurrency's purpose is against government's will. Banks are owned by governments to help moderating the economies. Reversely, banks finance gonerments. Whereas, cryptocurrencies tend to eleminate banks' roles. If goverments want to kill crypto, they definitely can. But why do they have to do so providing that crypto's impact on banks is very minor at the moment. That's not to mention, governments can leverage crypto as a way of laundering money or just simply earn profit.