I think the issue is that it's just harder to fit in. I remember being way ahead in some classes in middle school, and I actually ending up drawing the ire of some teachers when I had answers to every question (let alone corrected them). I eventually learned to disengage and just look out the window. But if you develop that attitude, you never learn how to cram in knowledge for tests, which actually increases the odds of failing some "less interesting" classes down the line.

Another problem that I've seen with a lot of really clever folks is that if you're told your entire childhood you're smarter than others, but you see these "others" sometimes get more successful, it's really easy to fall into profound cynicism. You never try anything and just undermine others on the internet.

Ultimately, stories like this are an exception, not a rule, even for kids who are truly brilliant. And yeah, it's easy to underestimate the role the parents play, mostly in creating the right opportunities and instilling the right way of thinking about the world. A child doesn't learn to play piano at the age of eight unless there's a piano in the home and a family member or a paid tutor to show them the ropes. Even for stuff like math, it's a parent's choice to buy the right books versus just giving the kid a smartphone.