In this link you can find an interview to Milton Freedman:
He defended this idea of how self-interested people were the ones who made a change in history.
In this interview they also talk about virtue, and how this quality is not the main force that motive people to make a change. Instead, the interviewer said that practically the markets reward this ability to manipulate the system: he’s referring to those who have found some way to offer value to society and have made a profit as a result.
It may be OK to motivate yourself to do something better by pursuing your own interest, but then we might reach a point (like today, in México) where the inequality between the people who receive the benefits from that change and the ones who don’t very big and unbearable for last ones. I think we have to search for some balance between the greed and virtue so when we have the opportunity to make an improvement in the society, the benefits not only stay between some people, instead I would like that they go for the ones who need it the most.