Why did Magnus Carlsen not defend the 2023 world chess title? He claimed it was too easy, but is there a deeper meaning/reason that he chose not to participate?
It's not that Carlsen finds the World Chess Championship too easy, but rather that he is losing interest in classical chess as a whole. The reason for that is opening preparation dominates classical chess, which means spending a lot of time looking for new ideas to gain an opening advantage. Carlsen does not find this very interesting, because it pits your computer against your opponent's computer, as opposed to your chess-playing skill against their chess-playing skill. The World Chess Championship is especially harsh on this, because the opponent will have serious support in the opening (with dedicated seconds), which means you need to do the same to be competitive.
You can see secondary effects of this fatigue from Carlsen occasionally playing moves like 1. a4 or 1. e4 g5 (as Black), to get out of well-explored opening territory as quickly as possible.
Magnus himself stated at the end of 2021 after the Nepomniatchi -Carlsen match that he did not have the motivation to contest another challenge unless it was Alireza Firouzja as the challenger.
FIDE reported it thus
So, these are Magnus’ own opinions and FIDE and the media reports at the time. I am unaware of other speculation or opinion in the open media.
I believe that Magnus decided not to compete in the 2023 World Chess Championship because there was more to lose than to gain. Everybody would be expecting him to win and I think that was a little too much for Magnus to handle even though he is arguably the greatest of all time and would probably win. If he didn't win everybody would think that he is falling off and may not be in his prime anymore. I hope this makes sense and hopefully helps you understand why he decided not to compete.