Thanks, glad it's of interest.

In this case, Harry was narcissistic before he learned about magic, when he had no realistic chance of boundless success (when he was one of many child prodigies, most of whom would turn out "pretty much ordinary" (Ch. 10), not the only magician-scientist), which is evidence that Harry's narcissism was due to his upbringing, not due to a realistic awareness of his own strengths.

I disagree with the premise that off-the-scale smart people are usually narcissistic, but I agree that many child prodigies are narcissistic. The work of doing research or another off-the-scale smart person activity encourages humility because of repeated failures (incorrect theories, etc.) on the way to new successes. Child prodigies (especially with a narcissistic parent, who distorts results to protect their own ego) can seem to go from success to success without apparent failures and while feeling fundamentally superior to others.