I earned a lot from Airdrops in 2017 and 2018 over a thousand dollar on 2018 alone thanks to referral campaigns, I never knew one can make reasonable money from promoting projects on this forum at that time, Airdrop was the only biggest way to earn free tokens and coins at that time
If I genuinely wanna talk then I hadn't earned a single penny from airdrops. I did certain airdrops but never got the luck to get some money throughout it. After that, I never participate in any airdrops and tend my focus to bounty campaigns and it has helped me a lot in managing my finances.
I've made a few dollars from airdrop, like stellers, blockchain, and so on. but, it is very difficult to calculate it every year. even this year I got an airdrop from one of the exchanges, although not much. Well, it's just that, calculating all the profits that I calculate right now is quite difficult because I'm the type of person who doesn't count the professions that I get. but it seems like I have to change that.