I think the "give poor people money or they'll take it" is a bit too simplistic. The basic reason we should give welfare is because that's what the majority has decided it wants to do. And in a democracy we do what the majority wants.

Now, the question is: why should the rich do what the majority wants? Not because the majority will otherwise kill the rich. The majority doesn't protect the rich minority from itself. The majority protects the rich minority from the strong minority. In other words, it's social order, underwritten by the majoritarian mass, that allows bankers and programmers to get rich instead of warlords. In a world where the majority isn't underwriting social order and the rule of law, there remains a ruling minority class, but they're different people than the ones that are rich under the existing system. Think feudal lords, rather than Silicon Valley nerds. That's why the rich go along with the majority. The majority protects them from the men of war that would otherwise dominate society.