participating in airdrop can gives you a free tokens/coins, but its not 100% that airdrop coins/tokens can gives you an earning by holding it after you receive from airdrop. mostly airdrop are good as penny and it is very rare to have an value in a long run holding. but its too easy to participate in airdrops that to join in bounty. because in bounty you have to do some task to get a tokens/coins.