If you're presented with abundance, everyone is taking a similar share and there isn't counterpressure from your peers (e.g., laws that we vote for), then there is no selfishness and thus no greed. To define greed you need a feedback loop.
We're simple dumb animals. We take what's available. If you want to talk about defining arbitrary limits on consumption that are disconnected from circumstances then you're basically out here preaching religion.