There could be several reasons for this: people want an instant reward and they transfer their coins into fiat money; or they exchange the received tokens into a preferred coins like BTC, ETH, etc.
I dont think many bounty hunter transfer their token into fiat. Hunters just prefer good coin like etherium or bitcoin.
They sell it just in exchange to get etherium or bitcoin because those two coin are the best to hold. Good coin is we want.