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.
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.
A favourite part of Hattrick is when you have an Eureka-moment, when you realize you understand some part of the game better than others. Or when you win something important, like a Cup, or gain promotion to the first division. My current goal is to reach the top-10 in Belgium again and to win a Cup with more of my own youth players.
I love Hattrick because it's simple. It is not taking much time to learn the dynamics, but you can tweak it forever. I love Hattrick because to me it is like Subbuteo or Risk. It is simple to learn but hard to master. It's still exciting to wait for 90 minutes to see the result of a game, four months to see the end of a season. I love Hattrick because it is possible to set goals for several years, to see your team growing up, to learn the names of the players, and to build memories about them.
The Hattrick community is colourful, it really helps expand the Hattrick world. You can find plenty of helpful managers that can help you with Hattrick and real life questions.
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!