secondly these ICOs never dump all at once, they slowly dump and price comes down slowly too. unless something spooks them to panic dump in fear of losing a lot of money because price is falling or another big ICO holder is selling their coins faster than them.
also (correct me if i am wrong) but isn't there some kind of lock time where the funds stay in an escrow or something before they can access it?
First of all, it's so crazy but we are numb now to this sort of millions people just play around with. Very worrying for crypto, but who knows, I am just a small fry.
secondly, yes, we have seen spikes on ETH even a few months back on polo. ETH seems quite vulnerable to small dumps. Anyway, these ICO owners know it and will only dump slowly, and probably for other alts even to pump those up. And make more!
And lastly, yes, supposedly there are escrows but this is one of those ICO where the escrows are themselves (they have 3 main founders/directors who must co-sign withdrawals). I have only seen one ICO with a third-party escrow (nvo).