I've seen lot's of people who complain to bounty hunters who dump their tokens after they get them. Why hate them? They have all the rights to sell whenever they want and bounty allocations are only 1%-5% of the total supply of the coin. I don't think it will do much to lower the price of the coin. I mean it's even good for the ICO investors as they will have a chance to buy more tokens with lesser price than the ICO.
Holding the tokens also doesn't mean it will make you rich. Some tokens get abandon by the developers so it would be better to sell at a good price than be left hanging in the end.
You are actually true, they have all the rights about the tokens but it's actually also true that bounty hunters is the main reason why the price of the token fall. Not only bounty hunters, but also early investors that got a big bonus on presale/private sale and sell their token directly after listed on exchange for quick profit.