The main reason why ICO's fall is that they don't collect enough money to realize their project. They mainly sell their tokens for ethereum, and many of them hold this ethereum till the end of ICO in case if they don't reach soft cap. But last months ETH has dropped and even if they reach 5k$ soft cap, as an example, at the end of the ICO that is still not enough. So they try to extend the project or just wait for better times. But in mid time they lost investors trust and interest, and project dies.