Greed is what keeps most of us going.... it is the fuel that drives us to achieve our goals, whether it is to become rich or to drive the profits of an organization. Whether we like it or not we are all greedy, it's apart of our nature, we can never have enough. The only thing we need to do is to learn how to control our greed and to do things in moderation.
For the most part I try to always be satisfied with the little I have and to be comfortable with my position in life. It is embedded in my mind that it doesn't profit you to be too greedy, unncessary problems come your way when that happens. Its just not worth it.