This phenomenon is anecdotally true at least. I remeber years ago reading an article about running that mentioned the same thing. People who are "age groupers" are way more outwardly hostile and competitive than actual elite athletes (so the article was saying) and the conclusion again was that the lower the stakes the more seriously things get taken by those involved. There was actually also an article on HN a few months ago talking about the same thing in swimming as a metaphor for something else - there's three lanes, the top, middle and recreational, top and recreational are nice, middle are all assholes.
