I know that lots of teenagers think they are the center of the universe but grow out of it. I am hoping that this is that.

Unfortunately, this is a specifically "gifted" flavor of this problem, and some people never outgrow it. (Ever read the horrific fanfic Harry Potter and the Methods of Rationality? The version of Harry in this fanfic thinks everyone but him is an NPC. The author is a full grown adult, and Harry is not especially meant as an unreliable narrator. The author's social group is full of people who think this way.)

A lot of people develop this type of thinking in part as a defense mechanism - they're excluded and bullied for being weird, and they decide that it doesn't matter because the people who do it are too stupid for their opinions to count anyway. And/or they develop this attitude because their parents had this attitude toward them: their parents only value them for performing intelligence and constantly point out how superior they supposedly are to "normal" kids. (Hi, Dad.)

I wish I had an easy solution.