Every time the reason is the same, they see a quick rich scheme and think that now it has to succeed and bring them the dream wealth. But the reality is different, there wasn´t any successful ICO that claimed guaranteed profit in advance. Look at EOS, they didn´t promise really nothing, but now it is one of the biggest cryptocurrency. 
Yes, the one who always promise a big things would happen are the one that failed in the end. Let the project along with the their products speak for itself. You really now if you are a good crypto user and have experience when you know that its a scam of not. I think the new crypto users are the one that fall in these traps. The way that the people thinks that it easy for them to become rich in these field makes them easy to fall into scams like these. Don't trust too quickly if they promise to give back your money with make it double or triple. You should also have access with your money not only them.