It's amazing how either of these two items can make the easiest-going person in the world, quickly become as aggressive and competitive as a strutting rooster.
Dan have you ever strived to be good at anything other than drawing attention to yourself. Have you paid any attention to the Anthropology of the human species? Have you paid attention to any species? The survival of any species depends on it's ability to compete against others within it's own species and other species. It's in the DNA and obviously some seem to have more than others. The reason for the competitiveness is it's rewards.
A good hunter who tries harder and gains experience eats' better.
A golfer who tries harder, makes more money.
A poker player who tries harder, learns the game is rewarded for it.
This principle applies to just about everything we do in life.