Aristotle is widely viewed as one of the greatest thinkers in history, while that does not make him correct it doe lend credence to my position.
Also, I can back my position up with logic and facts. Scary.
Argument 1: You say humans are naturally greedy, this means they want the greatest benefit with the least labour exerted to achieve it. This means under a communist regime many would barely work because they would still receive the same amount of compensation, meaning the other would have to work harder to cover for them, nut they would also be slacking. This would lead to economic collapse seeing as no one would be producing the goods needed to support all these people who are not working. Do not claim this is not true, it is the express intent of communism.
Argument 2: Communism works to achieve material equality, yet it ignores moral equality. By asserting the right of the poor to take from the rich it states that the poor are more deserving of those goods, meaning they have a greater right to them, meaning they are more equal than those who are rich or merely less poor. Therefore communism promotes moral inequality, a much more grievous thing than material inequality as material inequality can be overcome by hard work from the individual experiencing it, yet moral inequality can never be overcome by those subjected to it alone because they have "less right" to voice there opinion, and because they are less deserving of what they already have, allowing them to have anymore wold be a crime against those with more "moral right" to the good or service.