Why is this a self-building community? Because people are motivated to contribute to it. Why are people motivated to contribute? becasue they like to belong to a community, because they like the feeling of contributing, because they like to be recognized by their peers as good at something, becuase they like the feeling that their work and thoughts can be useful to others. Do people also like to show off, be first, prove themselves smarter than others? Sure, but I doubt that nodes illustrating those goals get upvoted as often as nodes illustrating the other goals. To reduce all of these various motivations to the word "competition" is one-dimensional and does nothing to explain why the atmosphere at PerlMonks is different from the typical slashdot / usenet / IRC venue where putting people down and showing off is the accepted norm.