The game is tailored for those wishing to spend money and there are many, many things for them to spend money on and gain huge advantages over everyone else and a game that is designed around competition makes this very difficult for players willing to spend a little money or none at all to keep up, and there are quite a few players willing to spend hundreds of dollars on it
The players at the top are by far the most rewarded allowing them to get further and further ahead of everyone else. There is no capability to catch up really if you fall behind so you have to keep playing every day at least 4 or 5 hours a day to remain competitive within the top 50. The activities are the exact same every day and the events are all the same at the same time every day so it becomes stale very quickly and if you have work, school or other commitments at a particular time then you will never make that event and fall behind. It is the community that keeps the game alive and the friends you make that keeps it interesting.