I strongly believe that greed is a vestigial trait from a time when scarcity was real. Ones instinct to preserve their bloodline would have necessarily involved greed, me and mine first. I also believe that some early humans developed the ability to overcome that instinctual drive, and we call that empathy. Life is actually a whole lot easier when you understand that greedy people are developmentally inept, their genealogy prevents them from having the ability to empathize with others. It's not to say it isn't a problem, but sometimes having an explanation to why a thing is the way it is helps understand it better.