I think your question is about as simple as it gets. One of the ways I frequently do well against statists (both on the left and on the right) in arguments is pointing out the arbitrariness of their positions. By asking the question “Where do you draw the line between greed and self-interest” you get right to the core of the issue, which is that any such attempted disctinction is completely arbitrary and subjective.
Not sure how many people here are sports fans, but I am reminded of the NBA player Latrell Sprewell who once rejected a multi-million dollar contract because he “had a family to feed.” I’m sure that in his mind he was not being greedy. I’m also sure that he employed an agent who explained to him that it was in his economic self-interest to hold out for more money.