You have a contrasting statement.
Bounties only consist of 2-5% of the total supply of the proposed tokens. And not everyone dumps their earned tokens right away. This do not have a big effect on the market price.
I am seeing many threads blaming the bounty hunters for the dump of the price of the coin, but there are many more valid reasons for that, first of all the price of many coins are overvalued, people buy at whatever the price the developers set, but take the time to look at other projects and their supply of coins and you will see some projects that are asking too much for their coins and you can say from the very beginning the ico price will have to crash, if you identify one of those projects but that you still think has potential in the future then the best thing to do is to wait until the coin hits the exchanges and buy it there.