Bobby Fischer was one of the top chess players of all time and was a certifiably insane nut job. There’s nothing normal about being a GM in the first place.
Niemann literally just won the biggest game of his life. He did something none of Duda, Alireza, etc have achieved. His situation was not normal. Trying to judge his actions based on whether it’s what Duda, etc would have done themselves in a situation they’ve never found themselves despite having had many opportunities to do so is silly.