Im pretty sure that technically people from the US arent supposed to invest in ICOs at all. And since theres no regulations on icos or altcoins...or even bitcoin as a whole right now in the US. Im not entirely sure theres anything the FBI can really do about this anyways. Im not an attorney and really dont have a full understand of exactly what kind or crimes the FBI can and cant pursue. So this is really just my opinion on the matter. Investing in ICOs is and always has been an "at your own risk" investment platform and until there are stricter regulations it will continue to be this way and there will continue to be scam after scam. It is up to us to do better background investigations into these icos to better inform ourselves and make smarter investments. Regulating icos would be great for preventing scams...but would likely make it worse in a lot of other ways.