Because this is a good way to make money. Scam is really a lot, the only way to protect yourself is to choose carefully. 'm working with the German project Vreo.io, maybe someone heard. They are doing dynamic in-game advertising and going to create marketplace for developers and advertisers. There is enough information on the Internet about the criteria for choosing ICO. The main ones
1. Uniqueness, necessity of idea
2.Clear target
3.Scalability
4.Transparency, properly allocated budget
5.Concept
6.Team
7.Distribution of tokens
1. Uniqueness, necessity of idea
2.Clear target
3.Scalability
4.Transparency, properly allocated budget
5.Concept
6.Team
7.Distribution of tokens
Also, maybe a good WhitePaper in order investors to understand this is not only a fancy designed website but also this people know what they do. And not just like most of the white papers with 10 pages in explanations how crypto and blockchain works (info from Wikipedia).