Let’s say your high school has some extremely hard-working, intelligent students like yourself. The majority of the student body are not, though. You then attend an elite college that only chooses the best of the best. Do you start to feel dumb since now everyone is smart?
You don’t feel dumb. You just realize that you got through high school fairly easily because you were smarter than most of the students, but now that’s not the case, and you have to work a lot harder. All the other students are experiencing that, too.