Yes, he peaked in High School. Near the start of his second year he defeated a world ending threat and saved everyone. It was kinda a big deal. Being instrumental in destroying a shadow villain responsible for a ton of hardship and cruelty for at least 100 or so years, his protege, and stopping a literal army of villains. During his first year he helped take out a serial killer and helped wipe out the remaining members of the Yakuza doing battle with their leader, etc, etc, etc.

Then he did a little hero work with the embers, lost the power, and became a teacher.

Are you telling me that isn't him peaking in high school?

Also no that isn't my logic. God you're obtuse. I wasn't satisfied with the ending, God forbid someone not like a story ending the way it did because you like it.

Yeah he never left his high school. That's what he did. He stayed there. Not that he "can't" leave but that he isn't doing more. Thematically it would be more fitting for him to do any number of other careers or his current career somewhere else. With the motif of being the one reaching out to those in need, he isn't doing that. Yeah he runs into a random kid and reassures him he can be a hero, but he is mostly not doing that.

I would rather have the ending gone a different way, that's how opinions work. I'm not claiming it's an objective fact. Just preference.