I didn't completely quit, but I went from organizing leagues (in Brazil, where I am from) and scrimming a lot (around 20~30 hours of TF2 per week plus the time I spent organizing leagues, casts, events etc), to playing pugs only (still in Brazil, around 10~20 hours of TF2 per week) and now to playing a couple of pugs only when I really don't have anything else to do (in France, around 5 hours per week). So, I would consider myself as a retired player, then...
Has your life improved since you quit?
Yes, by a lot. When I was really active, I was doing engineer school in Brazil. But I had no plans after the university due to the financial and political crisis in Brazil. So, 2 years ago, after spending some months in France and Italy, I realized I wanted to find something here and move out. After 2 years of dedicating myself to this goal, I realized what had became like a dream for me, and now I am working on a PhD in a field I am really fond of.
Do you get bored enough to feel the urge to come back to TF2 often, or are you satisfied enough with where you are (or dissatisfied enough with TF2 when you left) to not even consider it?
Yeah, I really love the game and I have been playing a couple of mixes per week with some really cool french guys that welcomed me to their community after I arrived here.
Did you have some other, non-videogame hobby to spend your time on, or did you exit into the world with no clear plans for what to do next?
I have been jogging a couple of times per week and plan to start playing Tennis again.
What was the main reason that you decided to quit TF2?
To accomplish the goal I told about in my first answer.
And, of course, why do you browse a forum for a game you no longer play?
Because I still love the game and I really want it to succeed.