"Gifted" students, as well as those who were labeled as "prodigies" or "geniuses" were often never actually taught how to study. Why bother? They're already acing the tests. And that serves them fine for a while, but then the expectations catch up to their ability, and suddenly the kid who was able to just whip through coursework is struggling, and they don't know how to study, so the only thing that they can know how to do is try harder, but they just keep failing and failing and they can't ask for help because they're supposed to be smarter than that. And then they just burn out. Meanwhile the kid who was always struggling, and had to learn all the different ways to study suddenly starts to flourish, and then the next thing you know, the kid everyone said was going to grow up to be a brain surgeon or a rocket scientist is struggling to get their life together but slowly making headway at their retail job, meanwhile the kid everyone said was destined to be just another statistic in the papers has just finished defending their dissertation and has a job lined up to start doing field research in the Arctic Circle.
By tbe same token: the "talented athletes" also had the same problem. They had a natural physical ability and never learned proper form, or how to pace themselves. Their early coaches didn't bother because "they can already hit the ball." But eventually the level of competition rises to their ability. Now they are getting beat, and the only thing they can fall back on is "practice more" but they can't practice right because no one ever taught them, and they blow out their ACL, and it never heals properly, and now the kid everyone thought was the next Wayne Gretzky is spending his days working the sales floor at the athletics store reminiscing about his lost potential, meanwhile the kid who kept tripping over his own feet and dropping the ball whenever he tried to throw it just got called up from the AAA league and is going to be opening Shortstop.