Many European ICOs recently that I saw, they all state in their ToS that the US citizens can't participate. Why?
If there is any country that is very complicated and can go to any length to get convictions even to the extent of another country, its the United States and even if I happen to create a service in the crypto world, I am sure to exclude USA citizens because I don't have money to pay lawyers and then being offered a deal to plead guilty over something you probably don't know exist in the first place but that's definitely no excuse to the judicial system for whatever reason.