I think K-12 education system makes high IQ people lazy because they don't need to try hard to get through a curriculum that was designed for people who learn more slowly. So this sets in as a habit.

I went through gifted programs and thinking back, I probably could have learned calculus by middle school if my education had adapted to my learning rate, but it didn't. We still had the same text books as every other 4th grader, we just covered more of the material in a year.