I kind of wish I didn't learn any advanced physics (I was reading Landau and Lifshitz when I was 14) in high school. It was constantly distracting to know how to derive everything (which meant skipping exercises), which combined with at least having many of the symptoms of ADHD, meant I never did any work and underperformed in every exam bar one.

That reading lead to me going up from the lowest math set to the top one but I wonder if I am over-read but not intelligent enough to have been allowed to study it on the natural progression. I was the only student in my class to display (publicly) any intuition or passion but I probably got some of the worst results.