No one would dump without a reason, everyone has profit in mind while buying or selling. If they found the token not worth holding they'll sell.
It's upto the project to convince it's investors/bounty participants to hold onto, not with words but with actions.
I read a trader saying that investors are also dumping because of an unstable market, they sell immediately the assets they have after the token listing with little profit in pursuit of other tokens being promoted.
We know that at this time the ico project was finished, the majority had a low than ICO price, this situation made investors sell immediately with the hope of not having a bigger loss, in contrast to investors who have large capital, maybe they choose to hold back
Dumping is a choice, that's right, so developers must be able to ensure how good their tokens will be in the future for investors and I'm sure many bounty hunters who have long been involved in the crypto world will also hold their assets