Airdrops allow to earn tokens of new and prospective projects for free and do not require a lot of money.
That is why airdrops very popular and a lot of people participate in them.
And also there are many people who have left the Airdrop program for reasons of not being paid and some being paid, but it is only suitable for Gas transactions in the wallet.
You also need to know that not all Airdrops are promising and able to provide a lot of rewards for everyone, because usually if the Airdrop is good, then the participants will also be limited according to the wishes of the Airdrop manager.