This is a hard question to answer because some ICOs were a super lucrative investments and some was a really shitty investment - This is a fact.

See here are the ICOs with the highest ROIs: https://icowatchlist.com/finished/best-returns

Here are the ones with the most crapy ROIs: https://icowatchlist.com/finished/worst-returns

So basically, you can either lose almost all your money or multiply it x1000.... it's not very symmetrical.

That's why it's best to only invest what you can afford to lose but also be a little adventurous - some people made really nice returns with ICOs.

Good luck!