Capitalism doesn’t assume humans aren’t greedy. It assumes they are and refuses to give them power over others. That’s the point. Greed under capitalism is constrained by consent. You only get richer by offering something others voluntarily choose to pay for. If you stop providing value, the money stops. Greed under collectivism is unconstrained. It’s backed by force. You get resources whether you create value or not, so long as you can moralize need or capture political power. Also, capitalism doesn’t pit competition against cooperation. Competition is how we discover who can cooperate best. Every successful business is a massive act of cooperation with customers, workers, suppliers, and investors. It just isn’t coerced cooperation. And the claim that capitalists never give back is empirically false. Private charity, philanthropy, reinvestment, and voluntary aid explode under capitalist systems and collapse under socialist ones. What you’re really saying is this: You don’t trust individuals to choose generosity. You trust the state to enforce it. That isn’t moral. It’s just replacing voluntary cooperation with compulsory obedience.
