why is chess so popular?

Throughout history, or just recently? Recently, this link gives some possible reasons: https://www.chess.com/blog/CHESScom/chess-is-booming-and-our-servers-are-struggling 

If historically, it is probably because chess is a complex game which a variety of people can play and the strategy and thinking element of chess is one which attracts many people. It is an amazing game and I'm happy to be a part of this chess community

Because its cheap to play , u only need a board , pieces and two idle minds 

And not even board or pieces with some players

One thing that really attracts me to chess is there's no RNG in anything about classical chess (obviously there's things like Fischer Random/Chess960 and other variant's). It's a game where the floor isn't that high but the ceiling is practically limitless.

Probably because nerds need a distraction from their day-to-day

why isn't chess so popular?!

Its the chicks.

Funny game

Yes, chess is a chick magnet.