That one I will never understand. I think it comes from there need to feel just as good as you are, they feel like they don't add up to you, so they compete to be better than you.
It is a very weird thing, and I think it comes from insecurities within themselves.
So, yes though I find it annoying, I can understand their motives in a way.
I think some have this strong desire for competition, even when there is no competition to win.
I'm in fact one of them. I do it without realizing I'm doing it. Its part of who I am.
I even try to stop from myself from doing it and I always end up naturally end up trying to compete against someone or a group of people or against a machine.
It forces me to work harder and harder and to push my goals higher.