Not every bounty hunter is dumping their earned coins/tokens. For example I've never dumped a single coin I've earned in any campaign. I join bounty campaigns only for projects I would like to invest in, and so, by risking my time, I'm avoiding to risk my money. But then, of course, the whole point is to hold the earned assets for years, not minutes. I have no time to work for dimes, which happens if you dump your coins as soon as you get them. In crypto the real money is only long term. Of course, not every project will succed. But some eventually will. And you need only one to be happy.
As someone looking to get into bounty campaigning your post rang true with me. I will put an emphasis on participating in projects i believe in.
I have also bought some BTC 'pizza' in my day.