i don't think they kill the project. the bounties and airdrops help the project a lot. imagine that the project without the bounties, the world won't know about the project. if the token/coins prices dump, i think it's because the projects run by some amateurs team member. the projects will die if the team abandoned their project and do not create the product properly.
I agree with your opinion, dude! Bounty hunters have a job to promote the projects. It makes no sense if they try to dump the projects when the bounty campaign is finished. The reason is that there's no benefit for them to do so! A project will be dumped because of itself, not anyone else! A weak project will dump anyway, do not use bounty hunters as a bullet shield!
They didn't even distribute the bounty, but the project collapsed. Like the Blockburn project, they did bouny with a budget of $ 15k. But after the bounty ended the price dropped more than 100 times and they kept delaying delivery on the pretext of price protection, really bullshit