I guess it's an innate drive in all humans, rooting back to when we had to fight over food. I actually thought I wasn't all that competitive until today, when my friend challenged me to beat his score in Robot Unicorn Attack.
Four hours later I beat his score and realized I just wasted four hours of my life playing Robot Unicorn attack but didn't regret a thing.
Which leads to a curious question
Do single player games like Final Fantasy, Zelda,Chrono Trigger, Metroid, etc. water down your sense of competition or heighten it when challenged?
Also, how competitive are you individually? What triggers your instinct to conquer?