There was a boy in French high school who seemed a bit impaired, in the sense that he seemed way more childish than people are at this age, so he was often mocked, and I don't remember him having any brilliant grades. Turns out he went into the top of the top of the French scientific universities (École Polytechnique).
Think Harvard level of prestige (countless top scientists, leaders and CEOs from there), but specialized in science, with way fewer seats, fully paid by the state and an extremely competitive entry exam that the best French students spend 2 to 3 years preparing for after high-school, with the vast majority failing and entering the next schools on the prestige list (still a lot of other prestigious schools under it). I guess he exploded his intellectual potential at this time, when others just implode into depression due to the high pressure.
I was floored when I learned about it and really happy that he took his revenge this way.