Being a BOUNTY and AIRDROP hunter, every time my token from bounty or airdrop listed to an exchange, it was very disgusting because the price is below the ICO price. Why this is happened most of the time?
Especially for ICOs with generous bounty rewards and not very solid/hyped projects, bounty hunters tend to dump their tokens for eth or fiat soon after listing. You can take this opportunity to also sell for eth then buy back a few days later even more tokens than you earned at first
IMO those involved in early selling also include private/pre sale investors who bought at 40%-60% price of exchange listing price.
Instead of just following all bounties blindly, one should also keep a note of private sale / presale price which will help decide at the time of exchange listing whether to sell or to retain.