Nothing. I don't care whether or not people use crypto currencies to do money laundering. I don't even care if they buy drugs and weapons with Bitcoin. It's not fair to just point at crypto currencies since basically anything can be used to get rid of 'dirty money' or to settle illegal transactions. People quite often tend to exaggerate in thinking that Bitcoin allows criminals to do this or that, while they completely discard the fact that all illegal things done with fiat, are far (like really far) beyond that what's happening with Bitcoin. People thinking that Bitcoin is being used by criminals should start questioning how the USD is being used to finance wars, terrorism, human trafficking, etc. I even believe that Bitcoin is a pretty bad tool to do illegal things with, due to how transparent everything is. Can Bitcoin be used to quickly move wealth from one country to another? Yes, but that's all up to the people themselves, and this is nothing illegal. Governments should look in the mirror and ask themselves why people want to take their capital away from their own country.