Money buys the thing happiness actually depends on: security. When people can't cover rent, medical bills, or food, stress eats everything else alive. That's not a theory, it's well-documented. And as someone who cares about the planet, I'll go further: money is what lets people choose sustainability. You can't install solar panels, buy an EV, or support ethical products on an empty wallet. Financial stability unlocks the freedom to pursue meaning, relationships, and even ecological values. Without that baseline, happiness is just surviving.