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.
With project famous they don't needed bounty hunter for promoting their coin to investor, just make advertisement with some website and many investor will interested with their coin, many ICOs without promoting as bounty campaign keep success and have higher price after listing on exchange market and keep stable with higher price after long term listed with exchange market.