First I played Hattrick to win, but over the years, I came to realize that reaching the absolute top wasn't going to happen for me - I'd need to spend too much time to fully understand the game and make use of that knowledge. So I stuck around because of the great atmosphere and people in the forums. Recently my interest in the game itself increased again, which made me open a team in a new league (Botswana), and I'm trying to be at least semi-competitive there.
One reason I play Hattrick is because I like the cyclical nature of the game. You start with an idea about what kind of team you want to build, then you train long-term (up to 3 years in real life!). While you build, you can test and try to comprehend the aspect of the match simulation that you want to master. I also like the tactical choices you have to make for each match. But the most important component is the community.
Why I stick around in Hattrick? I think it is love :) I mean, everything I can do to help Hattrick to stay as immersive as it is, is very important to me. I was a moderator, a translator, an editor - just because I felt that Hattrick, in a very peculiar way, was mine. Now I'm a National Coach because of the same reason. I think Hattrick is my game. I want to play forever and stay here with my friends.
When I registered, I liked that Hattrick has fantasy names instead of real players. That got me hooked. I also liked that all opponents were people of flesh and blood… and also that they turned out to be really helpful, showing me the steps you need to take as a new user to improve your team. Today, I am a good mentor myself.
What I like about the Hattrick community is that there are real people and you don't just compete against the computers. You play against each other, but you can also help each other in the forum and talk about everything.
I would say the community is the strongest reason I have stayed in Hattrick for so long. The game too of course. After having trained my players and played in the French Division 2 for a while, I started focusing on training international players to help the Moroccan team. Today 80% of the defense of the Atlas Lions was trained by me!