What exactly do those people do that is rightfully worth some orders of magnitude more pay than that single mother who suffers through every day does to make ends meet? What is so indispensable about them?

They are willing to risk large amounts of money. For instance, they build a factory that employees people and builds a tax base. This is a function that can only be performed by wealthy investors (or the government).

They don’t do it for altruistic reasons - they do it to make more money. Sometimes they succeed. Often they fail (Solyndra, for one recent example). That’s what I mean by “risk”.