TF2 is just really good at sucking you in. Most shooters are like this, but because each class makes you aware of something different (Spies on the other team means looking around alot and being aware, Demomen mean looking at walls and cielings, Scouts mean keeping an eye on the background for incoming threats), you really become "aware" of the game and get sucked in.
I, too, was all hyped up on my HLXStats. And I'd get pissed every time I lost 10. And once you get past 4K points, every death pretty much costs you > 10 points. It was very frustrating, and I've shouted things I'm not proud of.
After a while, though, I discovered the fun of not worrying about stats. It was at this time that I removed my HLX score box from my forum sig, so I wouldn't be confronted with it every few hours. And just started to play.
The offshoot is, by just having fun, you don't worry about dying, you get better and better at the game, and naturally start PWNING everyone else more than you find yourself PWNED. My score isn't awesome, but it's pretty dad gummed good now. ANd I enjoy seeing my HLXStats scroll by, it's fun. But now that I'm not worried about hoarding points, I have more fun.
And I bought a pro mouse with weights and jammed every weight in the pack into the mouse, so it's a laser brick. That was most of the solution.