I think that sailing through average classes on stored knowledge and then suddenly hitting classes in high school or college or grad school where attention and organization were actually required in order to master the material, without knowing ahead of time that there was a disability that might need accommodation or intervention, would be devastating and incredibly frustrating, and could seriously derail a person's career prospects if the problem wasn't recognized immediately, which it almost certainly wouldn't be.
I also think that the other issues that go along with giftedness, including the issue of needing to be around peers who get your jokes, would be unaddressed in that scenario. You still wouldn't fit in, but you wouldn't know why, and you wouldn't know where to look to find what you needed.
