The fact that almost all of the ICO does not have a working project or it is still in alpha, most investors who bought on the ICO will sell it early, weather for instant profit or FUD.
In most of the cases, once a "token" hits exchange for the first time after ICO, the price is always at below ICO price
(or even below Pre-ICO price). In here, most investors doesn't have any choice but to wait for that "right" time to dump to take profits etc. And then the "give up" thing will happen, some investors will prefer to make a dump early to minimize the loss. And then for people who got their tokens at outside ICO's
(in the means of bounties or any other promotional activities with rewards), surely they will hit that dump button the moment they got their tokens resulting for a bit shake on the market.
Honestly, the main purpose of most people why they are investing on ICO's is about the price and not the technology behind it no matter how good and spectacular it s.