The same reason the concept of "street smart" exists. People don't want to accept when they are being stupid.

Each an every one of us can clearly identify talent as the ability to do or create amazing things. But because people want to feel special, they twist and turn their perspective until they become special to themselves. "Intelligent? Well, you didn't make billions, so it must mean you're dumb. Athletic? Well, you didn't score that touchdown, so I could probably outrun you. Good at programming? Please. I could whip up a better solution in minutes if I wanted to learn programming."

It's basic politics. Skewing reality with faulty logic in order to gain something. Usually feeling good about yourself.