When you're working 18 hours days and burning out...he is mentally putting a cost/benefit to every single thing he does. I'm sure he decided he could generate more value doing something else (not a vague something else; a specific "I'm going to do this"). It's a coping mechanism and probably one of the few ways to stay productive in the face of insurmountable work.

Having put superhero efforts into a few roles, I can relate to that kind of behavior.