There's also the additional problem, from my memories of the school system, that our educational system emphasizes quantity over quality. I could never have passed an AP Calculus class because of the sheer quantity of work they pile on in the attempt to be "rigorous". Yet, when I got to university, I averaged an A- on my intensive advanced mathematics/computing courses: Differential and Integral Calculus, Multivariable Calculus, Linear Algebra, Discrete Math, Formal Languages and Computability and Complexity Theory. I've ended up doing some amateur type theory as research because, as it turns out, once you stopped piling on pointless busy-work, I'm pretty good at math.