I think the question kind of misses a point. Firstly, from a perspective of a poker player.
I used to play for living. No, I never made huge amounts and I was never a crusher, but compared to other opportunities at that time and the fact that I was still better than your average micro stakes donk, I could make a decent income. These days, I don't really play full time, but still I do play and to answer why - because I know that I am still better than an average player at micro (perhaps even midlish-stakes) tourneys. I don't put enough of a volume to beat the variance quickly perhaps, but I am not in a rush. At the stakes I play, I know I am +ev, so whatever, it is not like I am putting my livelihood on the line if I run bad for a couple of months.
You would be surprised how many people (and I come from a country where online anything isn't really a big thing) I know that believe that they can play good poker. They can't, they don't even have the basic principles in their head, but somehow they believe their game is the nuts. And just using the logic, if that's the case here, I can only imagine the exponential growth of numbers in other, more developed countries.
Then there are people who don't actually care about winning. For them it is just a distraction (I know a few of these as well). For example, it is still +ev for them to play Sunday Million and occupy themselves that way instead of playing slots and losing a couple of thousands. It is all the same to them; if the luck is on their side, they could end up winning the whole thing and that's really all they care for.
And now, let me give another perspective.
I love chess. I've loved it since I was eight years old and at one point in my life I was quite decent at the game. However, I've realized that I am not super talented for the game and I would never become top 1% or even top 5%.
Do you think that stopped me from playing? Of course not! I took some breaks and had periods where I couldn't look at the board, but it's always been my passion. I don't hope to ever become one of the best, especially at my age (not super old, but old enough to know that my "prime" has passed). Still, if I can be decent at chess, win some games and play some nice lines, that's cool with me. I don't particularly care when I lose, I only care for the things I could've done better.
You could mention financial element, but back in the day when I used to play more, I paid fair share of tournament fees to play in the fields where I stood no realistic chance. Who cares? If I manage to outplay one IM or God forbid GM, well, it was worth all the money. And guess what, I am looking into playing more tournaments soon, and getting crushed some more
It is just something I love to do, it is my pastime, and I would be an idiot to assume that I could consistently beat someone who devoted a big part of their life to chess.
When comparing the two, poker is immensely more exciting and, on the basic level, simpler to learn for an average person. That's where the 90k come from; most of them just want to have fun, to compete, to pass some time or distract themselves. Not everyone is chasing the dream. I mean I used to have a dream about becoming the top 1% in chess (or in poker for that matter), but once I've realized that wasn't going to happen, I did not stop playing. It was still fun, exciting, challenging and, as far as poker goes, profitable.
So there you go