The way I view mp is that its not suppose to just be about fun which people complain it can lack. Like being competitive in sports where you are good at the game , your not actually looking to have "fun" in the blissful way , your looking to test the limits of your physical and mental abilities. Its only human nature to want to discover yourself , improve your attributes , learn new things and be victorious in any way no matter how trivial . It seems theres a misunderstanding that humans should only rate things on "fun fun fun".
Ok, lets take this as true, wholesale.
CAL. I know people who've played video games semi-pro. Knew quite a few counter-strike players that dabbled in league play, plenty of well organized clans that did regular matches with each other in the spirit of competition. Only the assholes stacked and mp5 whored before going awp on public servers. Pump shotty snipers, tmp whores, pistol nuts. Those are the ones that were fun to dick around with on the public servers. I converted a few myself, getting the silenced colt whore with a 30-1 or better kill ratio to switch to pistols only really improved the game, for everyone. When you've got a game with two people dominating each others teams, it's really fuckin boring.
Winning isn't testing yourself unless it's actually a challenge to win. If you want to play to win and see just how good you are, fine, there are entirely appropriate times to do so. When playing a like minded, like skilled opponent who's also interested in challenging himself, go for it. When actually in a competitive environment where the whole point of playing is to win, you're obviously supposed to. Playing to the best of your ability to massacre some poor sap on a public server that doesn't have the foggiest idea what he's doing isn't challenging yourself, it's being a dick. In such a case, the challenge is in making it challenging, not winning.
On the other hand, there is also significant evidence that your theory on competition has a major hole in it.
Brett Favre for instance. Abject misery, every loss is agony for that poor bastard. He's the greatest quarterback of all time, and he's probably the least happy quarterback of all time.
If winning is everything, you don't have anything.