I think that airdrop now are give you little profit, because most of airdrops are scam, they give you reward in few amount of token and worth nothing in $, for now i prefer not join any airdrops because i get nothing if i join now, everyday people can make thousand airdrops and the tendency of scam project will be 90%.
You estimate about 90% of the project is scam, so about 10% can make a profit. That's enough for many crazy newbies because of it, although the value of these coins is very low.
actually they are crazy because they are noobs and think for free they are getting some coins , they even dont know what the project is all about , their only motive is to get free coins . after listing on exchanges they realize airdrop was worth only for 40-50 cents . airdrops were good strategy earlier but now in bear market nothing works perfect .