I think if there is too much SCAM appear it would reduce the people to keep their trust on ICO, and thus makes the ICO to suffer.
When that happen, a new system should be develop to avoid those SCAM and create a better way of investment, to rebuild the people trust.
Don't forget about people who already stuck in some ICOs that not success, i think people like them wouldn't back anymore for ICO and do anything else because it can make bad affect for that ICOs itself.