Prize hunters have worked for the promotion of the project, and have not received payment for hard work, a lot has happened, because the project failed, finally the hunters did not receive payment, I hope in 2020 it will not happen again, because they will really need the prize hunters to promote their project..
For projects that are not well-known it will really need the prize hunters to make project promotions, but for projects that are already famous will not need prize hunters, because they can succeed without making bounties, and in the past there were also many successful projects just by making ICOs only, and don't make a bounty.