Dumb.
Aldo wanted to go up, Dana wouldn't let him (reportedly). By that time, it would have been disastrous.
Jones refused to fight DC at HW because he had advantage at LHW (
source).
BJ moved up, got beat by an all time great, moved back down, eventually lost.
Conor moved up, lost to Khabib.
GSP waited until the weakest champ ever to move up.
Silva fought only lower top 10 fighters (yes I know Forrest was one fight way from the belt).
CCC fought twice and retired.
Khabib didn't even have time to go to WW even if he wanted. His prime and his championship era was too short. He retired earlier than most. If you want to rip him for that, fine. But don't rip him for doing what's basically
normal. Which is, fight well, earn belt, defend belt.