Why do strong players stop playing chess

As far as what you're talking about I think Olympic Athletes have it the worst.  Most of their young life plus another 4, 8, 12 years of training, and it's possible that 1/100th of a second is the difference between a medal and nothing.

But as for during the performance itself chess is up there with the most unforgiving.  One minor mistake and it can be practically impossible to recover the game.  Team sports don't seem to compare very well.  Music and boxing seem like good comparisons though.

Not really.  I think if you look closely you'll find that the large majority of those 2500-2699 GMs are younger than 35 years old and either (1) are below 25 years old and living like students (and maybe doing a little part time work) or (2) spend a lot of time working (including some who are teaching and/or writing about chess and others with "real jobs") and play as time allows, or (3) are subsidized in some way (government, scholarships, parents, etc).

Most of the 2500s and 2600s are NOT going to become 2600s and 2700s respectively.  Ten years from now, many (and likely a large majority) of the current crop of 2500s and 2600s will be doing something else and there will be a mostly new crop of 2500s and 2600s.

I think it is as I fear; chess is a young person's game and not a proper job.

Plus adults get burned out AND realize they're wasting their life pushing pieces around in a game. Morphy thought so and said so.  He said, paraphrased, don't waste your life playing a game, so he TRIED to pursue a lawyer's life. 

You need to be very, very good or you'll be very, very poor.

Insanity.  

All GM's do not make good money...Kramnik and Giri are top 10 players...quite the exception.  

What surprises me is the number of talented juniors that quit even though they don't have jobs or family or other grown up concerns. I think some players have been pressured by their parents to play the game but don't really like the game but like the winning aspect. Then when they get old enough to disobey their parents they discover their true passions. I remember when I was a child that I was particularly strong in a certain physical sport (which I hated) and liked to please my parents that I kept playing.

I think unless you are immensely talented and successful at it, it is not very practical to choose chess as a profession.  The effort required to be a grandmaster, much less a top player, is disproportionate to the rewards.

By way of example, when I graduated from college I was working at a boring job and started studying and playing chess alot. In about four years, I managed to get my USCF rating from about 2150 to a slightly over 2400.  I put a lot of effort into it.  And 2400 USCF is a long way from even an average GM.

Then I got bored with my job and went to law school.  Going through three years of law school required less mental effort that I spent getting from 2150 to 2400 USCF.  Actually, quite a lot less.  And I became just an average lawyer, but an average lawyer where I live makes more money that all but a handful of the top chess players in the world.  And a really good lawyer can make a lot more than the top 10 chess players in the world combined.  A lot more.  You could say the same about doctors, or people who work in tech jobs. 

Chess is a fun game, for sure, even a beautiful one.  But in terms of practical rewards for effort invested, it is probably one of the worst professions you could choose.

I imagine becoming a grandmaster, if you can, brings a lot of job satisfaction, as would becoming Atticus Finch.

That has nothing to do with what I wrote.

The ultimate prize for a chess player is being a grandmaster.........unless u r very talented, u r not going above that. The old (in terms of the no. Of years played)grandmasters and a lot of strong players too realize that at some point going further is impossible. That is why they start to quit chess.......and try their luck elsewhere...........this is the only big important reason......and this should end the topic's answer here......!

Edna St. Vincent Millay (February 22, 1892 – October 19, 1950)

"First Fig" from A Few Figs from Thistles (1920)

Jeroen Piket a Dutch GM quit in 2001 after very promising performances against both Karpov and Kasparov... I guess he concluded he could not be nr. 1 and got a regular job instead. It takes a special type to be a GM without prospects of winning anything big.

think about chess. coffee, cigarettes, soda, hours on end sitting, not to mention heart arrhythmias

and energy shots!

The missing word here is "Plateau."  When you realize you have reached your personal best at whatever level, the challenge is gone and you just play for fun or mental exercise.  Chess 960 is a desperate attempt to make the game interesting.

I challenge the assumption that strong players stop playing chess any more frequently than weaker players. In fact, I think they continue playing on much longer than weaker players.

The difference is that no one notices or cares when weaker players quit.

It's an observation bias.

maybe they don't like the people.