Books, etc will be a good "retirement" activity and income for Magnus. It is unlikely he doesn't have plans.
Why there is no book written by Magnus Carlsen?

There are some EXCELLENT books on Magnus Carlsen. One of my favorites is Tibor Karolyi's Endgame Virtuoso: Magnus Carlsen.
https://www.amazon.com/Endgame-Virtuoso-Magnus-Carlsen-Extraordinary-ebook/dp/B07GLBKV3F/ref=sr_1_1?crid=C4Z07H3JLFVR&dchild=1&keywords=endgame+virtuoso+magnus+carlsen&qid=1588383018&sprefix=endgame+virtue%2Caps%2C181&sr=8-1
Magnus is putting all his efforts into modern media. I don't think he'll write too many books or even articles. Ever. But there are quite a few videos available on another site.

He doesn't want you to know his secrets duh
Magnus does banter blitz where he discusses what he is thinking in real time. He analyzes his own games and those of his chief competitors on a regular basis. He plays publicly on another site nearly every day.
Magnus has very few chess secrets. He has published far more game analysis than any previous world champion. He just hasn’t published anything in book form.

Teaching is a skill that's separate from chess.
Writing books is yet another skill that's separate from chess.
He's only ever played chess. He'd obviously be a lousy teacher and writer, and as some have suggested, even if he were good at it, he doesn't need the money.

giving away his insights in a book would be kind of self-destructive. At least, if he must, he should save that stuff for when he's officially retired from competitive chess.
Yeah, I don't think it works like that. Chess at the highest level isn't won with tricks. It's not like his dominance is something so pathetic that it'd disappear if he talked about his thoughts during a game... and as smyslov fan pointed out he already does that all the time, in banter blitz.
He's never said that.
He has said he studied a lot and played a lot and that's how he got better.
When asked why other people did the same and they're not as good as him he said he didn't know why.

Reading the comments it is clear that less than 10% of the people posting have ever listened to Magnus or watched his banter blitz.

giving away his insights in a book would be kind of self-destructive. At least, if he must, he should save that stuff for when he's officially retired from competitive chess.
Yeah, I don't think it works like that. Chess at the highest level isn't won with tricks. It's not like his dominance is something so pathetic that it'd disappear if he talked about his thoughts during a game... and as smyslov fan pointed out he already does that all the time, in banter blitz.
He's never said that.
He has said he studied a lot and played a lot and that's how he got better.
When asked why other people did the same and they're not as good as him he said he didn't know why.
He is a very humble person, his favorite world champion is himself when he was 29.

gdzen wrote:

Too busy doing other things. Has no current interest in writing a book, or collaborating with an experienced chess author to write a book. Personal reasons. All of these . . .
Many good reasons for not wishing to write a book at this time.

Oh, well yeah, no top player is going to publish cutting edge opening theory. They keep that stuff secret for sure.
And if Carlsen did publish a book like that it wouldn't sell very well, because other than a few starry eyed amateurs, most people would realize it's not useful information for them to know a new idea on move 22 of of a sideline very few people play.

Oh, well yeah, no top player is going to publish cutting edge opening theory. They keep that stuff secret for sure.
And if Carlsen did publish a book like that it wouldn't sell very well, because other than a few starry eyed amateurs, most people would realize it's not useful information for them to know a new idea on move 22 of of a sideline very few people play.
Who said that it has to be an opening book? If he writes a book it will most likely be about his own games.

I mostly need to know how he thinks in the middle-game stage. I dont mean 'tactics'.. I mean long term strategy.. What does he try to do at large-scale and when does he do it or when does he change it? What kind of signs can change his route.. whats the worst scenario he afraids to live. Things he avoids and the opposite..
The more you improve, the more things become automatic and unconscious. Plus he's been playing from a young age.
In other words it's like asking a native English speaker to help you by solving a question like this:
I know the answer is #3 because it "sounds right" and the others don't.
The actual explanation (I took this from online) is
"With an indirect object, the transitive verb and preposition should be a unit"
But I barely remember what an indirect object is. I could name some prepositions but I couldn't explain what exactly a preposition is or does and I don't remember what a transitive verb is.
In the same way Carlsen doesn't know things by name, it's just automatic for him. Certain moves "sound right" (so to speak).
See this video at 5:20 and 15:27
https://www.youtube.com/watch?v=k1SCXb2WA2U
16:06
"Ok, I'm not the best person to teach . . . "
---
But of course Carlsen isn't just a native speaker, he's the world champion. So it's not like asking me English questions, it's like asking some famous author what he thinks about while writing. The answer he gives you will not be useful because you're missing a mountain's worth of context, and decades of experience.

Another reason it's not useful is because in chess, the best move almost always looks good. Only in special cases, like tactics where you're sacrificing, does the best move look completely horrible.
It's like telling a beginner "I put my rook on the open file because it controls a lot of squares"
The beginner thinks, "oh, that's easy, I can do that." And then in their next game they put their rook on the open file and lose.
At best, knowing why a move is good gives you half the information (sometimes much less). To really understand the move is good you need to be able to explain why other moves that look good are not the best move... and that knowledge is usually hidden from a very strong player. The other moves don't look good because they're obviously bad... they're obviously bad because I've made thousands of mistakes over 10, 20, 30 years of playing, to the point I don't even notice those moves exist anymore.
Carlsen is arrogant, I never see Caruana saying "oh it's just all natural I just know" as if hes Mozart or something lol he's just good at a sport.
It doesn't matter how good Magnus is.....the publishing industry has drastically changed over the last 30 yrs.
I agree. There's been multiple ways of either publishing interactive e-books, with limited success, or just straight out converting books to be played through an interface like the Fritz interface.
The newest craze is using QR codes to scan a page and have the games pop up on your screen.
There is a need for computer books, but it's a much harder sell than training stuff that's designed to be used on a computer from the beginning.
Perhaps books using the Fritz interface is the best option so far. I'm not even sure anybody still is releasing new books in that format.
I haven't tried the QR code books, but I'm guessing it's a way to be similar to ebooks on Fritz interface, but usable on a variety of devices without needing a specific program to run it, other than a program installing the first time you use it. (Not sure it's still on beta testing at this time.)