They don’t teach the A students how to work with the B and C students. In my experience, at least, all the A students were kept together in “honors” classes. We were led through harder material faster, while the B and C students did their own thing. There’s some value in that, but it also creates problems down the road. In real life, I’ve never worked on a whole team of A students.
Sometimes maybe you’ll be the smartest person in the room. And maybe you’ll assume everyone that will recognize that, and that they’ll listen to your sage advice. They won’t. If you’re really so smart, listen: You need to understand how to work with them and how to help them. If you can’t do that, you’ll resent them. And you will move on to the next “them” and quite probably resent them too.