How can people be so competitive?

I don't understand how people can get through college with 4.0 with publications, perfect gre scores, and whatever else. Being a physics student, I've done research, gre's, and everything else ... but getting into graduate school is something else. It seems that the difference between an A and a B is usually a question on a test, and for people to perform so flawlessly and perfectly completely irks me. What usually pisses me off is that people I've helped out on homeworks and such get better grades then me ... usually getting that A. I'm only a B B+ student, so I can't understand why people complain when they get an A-. How can people be so crazy about grades?