To start with, the rewards for work done is payment. So in crypto currency, after airdrops or Bounty task is done. The rewards is to be paid in tokens. What Bounty hunters choose to do with their earned tokens is nobody business, this is why we call this place a decentralized space.
Also, most traders, and crypto users started one way or the other as an Airdrop or Bounty participants before learning and perfecting their way to trading stardom.
Crypto currency Bounty hunters, are promoters, marketers, crypto user, crypto hodlers and they full all exchanges too