"Greed" is defined as "excessive or rapacious desire, especially for wealth or possessions." Personally, I would define it as "wanting more than one deserves or is entitled to."

The trouble with this: who defines what is "excessive," or what a person "deserves" or "is entitled to?" Under professedly Communist regimes, that has always wound up being the government.

In reality, "greed" is simply the flip side of envy: a person who is "greedy" is someone who has a lot more stuff than I do, which is perceived as unfair. It is not an objective standard by any means.

Communism is fundamentally flawed not because people are "greedy," but because they naturally act in their own self interest,

Is it only me who is wondering just what this has to do with Aeronautics and/or Space?

Since you said "seriously," I'll answer. Because otherwise no one would invest in any business that they were not personally operating. Suppose you own some shares in a mutual fund. Is it reasonable to hold you personally responsible for actions of businesses whose stock you hold? Exxon has millions of shareholders. Is it reasonable to track down each one of them and shake them down for the costs of the Exxon Valdez cleanup? How many of them had any *control* over Exxon's corporate policies?

Limited liability is an essential component of having any sort of industry beyond the cottage level. How likely would you be to invest $10,000 in a startup business if you knew you would be personally liable for all the business's debts if it failed?