That's not completely true. Yes, greed is a part of humanity, but it does not necessarily mean a bad thing.
Let me give you an example, out of many: You are a greedy businessman. You'd prefer to open a business in a country where you are friends with the politcians, or in a country where the free market competition is dominant?
In a free market your greed will turn into willpower to offer a better service to society. That's the only way to grow richer. Society would not buy your products if you are throwing prices high. Or if you paid low salaries your workers would not work well, your products would decrease in quality, and you would lose a portion of the market to the competition.
You could say you could form a cartel with other businessmen. Tell me, until when you will be able to mantain a cartel, while there are more and more people who wants to compete with you?