alt Hacker NewsThe reason the top pros like chess960 is because they don’t need to spend hundreds of hours of opening preparation, they can just sit down and play.
Caruana (the guy who lost to Magnus), mused in a podcast that chess960 feels strange as a competitor because he doesn’t really prepare (because there are far too many openings to study) and said it feels like he’s getting paid for much less work.
There are 960 possible starting positions and the chosen one is known at the start of the tournament where players are given 15m to prepare. I have observed that GMs aren't surprised when they see the board. They usually go "ah it's this one with the opposite bishops" or something similar.