It depends on how you define greed. If your definition is inclusive enough, everything becomes greed, e.g. boy helps old lady across the street because he's greedy -- helping others makes him feel good, so he hoards hedons.  People who are greedy for *money*, OTOH, are bad people; the sort of people I do not like.  It follows that I shouldn't wittingly create a system that rewards such greed. Trying to create a system which makes greed work towards good is a Goldbergian enterprise. At best greed could null itself, everything else is trying for perpetual motion.