I have participated in over 100 airdrops since I have been active on both forums. It's easy, filling is the point and waiting, and then, if you wish, you can enter and trade afterwards. The biggest airdrop was $750. Back then, even on the DeepOnion forum, there were a lot of easy airdrops.
Correct me but this is year 2017 to around 2018, right?
That's when ICO's are very popular and so this coin also became popular especially in Bitcointalk.
Anyway, it's good for you that you manage to join that many airdrops in a short amount of time. As for myself, I tried to follow many airdrops a few days ago, but aside from me getting overwhelmed because it's that many, I don't have the extra funds to join on them as well because most of them requires you depositing some money in order to get points that will be exchanged with tokens in the future.
As for my biggest airdrop, it was DYM token. Dymension gave me around 60+ I think, and with its starting price on Binance of $5, I got around $300 for free. Those who staked more got better for sure.