Based on my experience, to gain enough profit from ico investation is at least you must invest 1 eth. May be your asset can increase to 5, 8, 10 or more eth (if you choose the right ico, this is lucky factor).
In fact, Most of them are shit project. Just imanagination based (not based on real project), just trading token. The function of the token is to increase the-project-owner-and-friend-fund/asset so fast.
That's why I do not like to take a part on those icos investment, although if I have many ETH balance on my wallet. I do not want to support fraudulent icos as well