Many European ICOs recently that I saw, they all state in their ToS that the US citizens can't participate. Why?
Not only the ICO but the other investing sites too because some of them are HYIP and PONZI scheme in which the US are just protecting the welfare of their people. I remember a bitcoin trading site ethtrade.org was banned in the US but the site reason is all about taxation but after the August 1 the site is truly a scam and US just save the US citizens from this site.