Note that societies have actually come a long way in the last decade or two, current setbacks notwithstanding. With all the noise the certainly not perfect US political system produces, it's easy to overlook how many things actually work quite well, both in the US and in other democratic countries.

Other crimes that cryptocurrencies may be useful for are obviously tax evasion, and any sort of money landing from all sorts of schemes. I really don't see a reason why we should rethink the basic principle of fair taxation, or, in general, why we should abandon the current system based on law for one where might is right.