There's no one word answer. Some have made 10X and more returns on ICO. A lot of due diligence is required to research and understand what the company raising funds intends to do with the funds, their roadmap ..
and more research required in guessing if the company will succeed given the current marketplace conditions.

If you don't shy from research, can invest some money that you can afford to lose, and know how to statistically diversify your risks.. ICO could be a good idea. If not NOT..