it is an abstraction of a particular way people interact economically
It is not a particular way, it is the natural way people act
You mean fear and greed, as you said, the 2 basic instincts? Okay, but what about "most people have morality [...] they have conscience"? Did I take your words out of context and you meant to say something other than what you actually said?
I dont see a contradiction here.
Greed doesnt mean that people will do bad things to get stuff, it just means that they want to get stuff, but will go only as far as their morality tells them to.