In this scenario Subaru is the straw that broke camel's back. Or in the pic related, he's the mouse. Sure, his contribution was the final piece of the puzzle that allowed them to fix the problem, but he kinda forgot that "final piece" is fucking useless if all other pieces are absent. His contribution is critical, sure, but he's not really the greatest contributer.
tl;dl: time powers overinflated his sense of importance, he took everyone else for granted.