I'm still actively participating in the airdrop. I get 1k bucks recently just from staking retroactive (XPL). I get even 5x ROI from participating in the pre-sale by ZKC for its prover participants.
But that doesn't sound like an airdrop, based on your description it seems like you made
an investment (or rather made a bet) and made a profit on your capital not on free coins that you got for free without doing anything or risking anything which is the definition of an airdrop.
In that case you could have made similar 5x returns on a lot of other altcoins that get pumped like that from time to time.
It seems more like a TGE. Presales, ICO, IEO, and other earlier investment are not airdrops. So yeah, you are right here.
Airdrops are free distribution of tokens to people’s wallets either by performing simple task or just spreading the tokens to have more holders. Most airdrops tokens are freeze when the token launched, only TGE investor are allowed to sell and make profit. After the coins are dumped, airdropped tokens can now be sold at lower price. In conclusion, he made profit because he was an earlybird investor and the project owners put them first before airdrops users.