>>282981823 (OP)
There's a few things that I personally got from it. It's a classic Bildungsroman, a young person discovering who they are.
Don't be a self absorbed narcissist who revels in their own talent and alienates others. There may also be others out there who are more talented than you. Be humble. (Hanazawa)
Mob is a mob to almost everyone else despite being an esper. I think this is a double meaning in that there is more to people than you think. Everyone is the main character of their own life and has their own unique insights, experiences, and turmoils that they're dealing with. Also, each person has unique traits and skills that make them "them", you are not truly a "mob."
Above probably ties into something along the lines of being willing to bare your soul to others to reveal your true self and make actual connections. Only by acknowledging yourself will you be able to improve, and be happy.
I'm not sure how to articulate this one really. Mob wants to realize himself as a person by becoming someone he and others can respect by self actualization. He hates his esper powers as it's something that's just given to him, he wants to earn something through his own work.
The fact that he could level mountains, but works himself to near death in the bodybuilding club shows there is value in hard work and earning things yourself. It builds character, and discipline, etc.
Mob's brother is also envious of his esper abilities and is willing to do anything to have his own as well. Mob just sees it as a nuisance. Probably showing how you can never understand another person's world view truly, and "the grass is always greener".