What is it about us guys that we have top the next person no matter if it is a good or bad thing. We are so competitive and we look for the edge in anything. Don't get me wrong because I love it, absolutely. It is so in our blood. For example, if one guy tells another guy that he sweats a lot, the other will go, "...oh you haven't seen me play basketball. I sweat like a pig (by the way pigs really don't all that much)." We are talking about sweat here. Even if we are talking about things like, "my car has the worst gas milleage" or "I have the ugliest (insert whatever here," the other will still try to top you.
In the end, I believe that God made us like that for a reason. I think the reason is so that we can stir each other towards him. Yeah, girls have an element of competiton but from what I understand, most girls compete more with themselves than with other girls. But guys won't compete if there wasn't another person to compete with, most guys anyway.
In the end, I think it is great. A lot of people can't handle it but I also think it is one of the things that makes us feel like men because we all seek validation through the eyes of other men that we hold in high regard, be it Jesus Christ, our earthly father or best friend. If we don't have that validation somehow or somewhere, we begin to question our manliness. Girls notice that when something is missing. Many people refer to what is missing as the "IT" i.e. "that guy has it." Thats a different explanation for another day. Some guys are born with "IT" however most guys that have it aquire it from validation early on in their life. "IT" or the lack thereof can make or ruin a guys life.
PS: Having "IT" doesn't mean you can't be sensitive or emotional. Having "IT" means that you also have the capacity to be sensitive to situations and able to act out of knowledge and experience rather than feelings.