Answer:
The general idea is that wishing for anything beyond basic survival is greed. It is productive because having something you wish for, you are likely to work towards getting it and thereby likely to produce more than someone who wishes for nothing and is content with merely existing.
It isn't too hard to imagine scenarios where greed is unproductive, like stealing (stealing is still work, but not productive work), or even counterproductive: If most people in a society were to live on stealing from each other, overall production would go down - the stealers would not produce and the producers would see no point in producing when the result of their efforts just gets stolen anyway.
Still, without greed there are no wishes and no reason to put in any effort in any form, and neither stealing nor producing would happen.
For an opinion piece on "too much greed is counterproductive", see related link.