Can you even have capitalism without greed? Greed is just a pejorative term for self-interest, which is a core assumption in the treatise of capitalism. It can't exist without it.

It just needs to be limited. You can't have lassis-faire capitalism forever because the people who are most successful will change the initial conditions and it will no longer be lassis-faire. So you need some kind of control outside the free market. The free market alone is not corruption-proof in any way.