I can understand Thor falling off. Guy took more L's than anyone else tbh
Watched his brother ''die'' 3 times and he couldn't do a damn thing
Parents die and he has to leave his girl
Loses his home realm saves whoever is left only for em to get murked while he's head honcho.
He can't do a damn thing about any of these. He has nothing left except vengeance...and even that he doesn't have because he screws that up
He should have gone for the head
He not only has survivor's guilt now he gotta live with the fact that he let half the universe get turned to kitty litter
He DOES go for the head next time
Only to find out thanos destroyed the gems and he's happy to die
People have killed themselves over far less
All of this is true. That trauma he had to live with is unbearable to most living beings.