Many of the ICOs which I participated were shunning away USA residents and anybody holding USA-issued passports. Maybe because they would not want to get entangled with possible legal battle with SEC or any government agency. It can be a big hassle if one day USA SEC would declare that ICOs are not legal. Right now, the SEC has not yet issued any solid pronouncement regulating ICO but we don't what can be in the coming months.
The boom in the ICO market right now is really attracting big and small participants and there is now a trend for niche business to also join the ICO bandwagon. But while this can indeed scam issuers, regulating ICOs can do more harm than good. What we need is a way to do due diligence so we can guide ICO buyers away from possible scams.