It's very clear from looking at chess, but also e.g. online gaming and sports that people in their 20s have the strongest cognitive capabilities, especially "processing speed".

But on the other hand, the world is very complicated and you can't know much in your 20s. I'm today a much better programmer than 10 years ago, even with slightly less brains. You are not going to write an impactfull novel without live experience.

How that declines varies and some people still have most cognitive capabilities in their 70s.

Yeah. there is some obvious logic that one can use here without having to look at data.

Not everyone survives to write to an old age.

Old people have health problems that can prevent them from work, like going blind.

People who write a great work at an old age will not have the time and energy to do all the non-writing parts of making the great work seen by readers - which has always been a big part of writing. Like getting their book in bookstores, advertising it, etc.

If someone is a very talented writer they are likely to write great stuff before they get old and may spend their old age preening and working on their legacy instead of new works. They will already know they're a great writer, so the drive to make another great work is lessened.

If someone is already an accomplished writer more of their time will be taken up with invitations to speak, being on award panels, doing interviews, writing introductions.

There is less financial incentive to write a great work when you're very old.

It is harder to be part of a literary salon full of smart people that help you grow your creativity when you're very old.

As people grow older they become more alienated from the zeitgeist and are better at connecting with their own generation.

Sort of confirm: I'm older, and my mind is fine, I just don't care as much anymore. I'm comfortably numb as the song goes.

100% true about chess but I think there's more nuance to it.

In 6th grade, I had gone to a chess coach who were a friend of my father (technically my father knew his father very well). It was my birthday/a day close to it IIRC and I wanted to learn chess. He was an international-master (or close to it) /National-master (I think he just had one norm less) and he told me about his story and everything, but he said that in a way, he does feel like if he had put the efforts within something like finance for example, he really could earn more than 10 times the money but he said that he really loved chess with a passion. I think that is another element and I think he was within his 30's. Not everyone makes it even that big within chess aside from a very few at the top

You are sort of right in the manner that, as teens grow and the focus of life/dedication from teenage years on solely getting good at chess, diversifies into for example relationships/money-aspects, the mind simply doesn't have enough competition to play chess Comparing this to a 18 year old or 17 year old who just wants to get best at chess and doesn't really want anything else other than chess with their complete and utter dedication.

(There is also another theory recently within Chess of the pressures of being the world champion, from Ding Liren to Gukesh, both have faced tremendous losses after being the best, Gukesh has even lost 75 points after being the world champion, which I believe also has to be because of how many eyes/the pressure building up)

I still like playing chess but all of this makes me also appreciate all the chess players as well in a bit-more behind the scenes manner too. At professional level, calling it taxing sport mentally might even be a bit of an understatement especially for the people within their 30's.

another thing I personally like about Ding and Gukesh both is that they are both humble. They might win or lose but with the brief time that they both had/will have the crown is with their own humbleness. I really like them both a lot. Hope history remembers both their struggles and their humbleness.