i really do not know why do we need to dump the coin. That thinking is illogical, as if we just earn coins in one posting. Bounty hunters should not also dump coins. Imagine, for over 3 to 6 months and even more, we are working for the project. Then, after the campaign we just selling it 100 times than its ICO price. Investors also would not to sell coins because they might lose capital once they did it.
You must consider that there are many bounty hunters from countries where an opportunity to earn $ 100 for 3 months of work is a lot of money. that's why they sell right after they get the opportunity