I think the dumpers are so scary especially if they get altcoin in bounties and that you're late to make sure that the price drops and you're losing money so your altcoin got the first bounty to keep it first sell it immediately so you do not lose it
I think all this is due to the fact that first of all investors sell tokens, as they have a big bonus when buying them. Without the bonus, no one would buy them as they would always have to wait for > ico prices. And then the hunters are connected, most of which are only interested in receiving cash.