I want to prove...

Today I was thinking about why some people work so so so hard to prove something. I realized that we all want to prove something. We want to prove that we are clever, or faster, or better in something. But why do we have this urge to prove?
I think I can say that the reason is deeply rooted in people's childhood. Kids are mean. Some of them think they are bigger, better in everything, and they start bullying the vulnerable children.
These children are going to be adults, and they want to show everyone that they are not stupid, they are talented, clever...etc.