Not true of me, in that I had the good fortune to go to NCSSM, and had lots of resources at home (computers early on, lots of books, supportive parents), and could teach myself from reading books. But I have run into plenty of very smart people who have gone nowhere because they've never been challenged. It's easy to be lazy when you're clever.
The best thing I got out of public education (before NCSSM) was adults letting me do what I wanted to do. That is, I convinced my teachers to let me be excepted from all sorts of requirements, and I spent the time thus freed....reading. No, I didn't learn any math in 5th grade at school, but even if I hadn't been exempted from math class, I wouldn't have learned any math at school. Better that time spent reading sci-fi or Martin Gardner, in my opinion. But again, not everybody is like me. I probably could have done "more" if I had a class in algebra or some such when I was 11. But that would have taken away time from my "extracurricular" education.
Anyway, I like the sound of that Davidson Academy. I'm sure I would've enjoyed such a place...if I could've got in. I doubt my IQ is that high. (Maybe that's why I didn't have that much trouble with regular school as those profiled.)
FWIW: When I went to CTY, my parents forbade from taking any math classes that would get me even farther along in the regular precalc/calculus arc. So I took computer science one year and problem solving the next year. I learned propositional logic, group theory, algorithms and computation complexity, and a few other odd math topics that I would not have learned til I got to college. I learned far more math by being forbidden taking "official" math. Funny how that all works out.