You have not done the needful to the heading of this post as suggested by people with more experience than you on this platform. I'll suggest you do that to get more feedbacks to your research. Good luck

To answer your question, people invest in a lot of reasons. Chief of it is make profits as ICO's have been known to have high ROI's in the past which really isn't the case of late. Another reason people invest is because they plan to actually use those tokens on the platforms of these projects, so they get it cheap during ICO.