Being smart enough should have nothing to do with anything, however, I do understand what you are saying.
During high school, I thought a lot of my friends were smart. They were getting the grades on all of their calc homework and seemingly understood everything and I felt like I was behind somehow. But, then I realized it was all because they were on a sports team or they cheated off of the select two people that were actually smart in high school.
During college, all of those guys who I thought were smart ended up majoring in elementary education. One of those two people who were actually smart graduated with a degree in economics, finance, and mathematics, a triple major.
That one person ended up going to a tier 1 school (U of Iowa) with a 34 on their high school ACT, a 4.0 GPA in college with a triple major, and then the top 10% on the LSAT for the US. Now that kid is smart.
But everyone else? You, me, the guy in the cubicle next to me? They aren't necessarily smarter than me, but they've been here longer.
So, I guess the point I'm trying to make is that no one is really smarter than others, they simply have a great drive and determination to make it to a certain point in their life. I think if you look far ahead and see a point you want to be, it gives you an idea of how to get there and what to do. Keeping your eye on the prize is never easy, but those who do and succeed, I would say are the most driven and determined individuals—the smartest individuals.