Mexico will pay for the wall under any circumstance.
It will pay by the cutoff of drug money flowing to it; Fewer drug shipments making it to the US means no corrupt dollars back to Mexico.
It will pay by all the Mexicans that cannot cross the border so easily, many remaining in Mexico to burden their society rather than ours, while many return to Mexico voluntarily because the way back & forth is much harder, further burdening the country rather than ours.
The savings from a virtual end of Illegal immigration will pay many times for the wall. Savings in education, health care, & welfare will be HUGE. Let the Mexicans pay those costs. Money saved is as good as money earned.
Without a “Get out of Mexico Free” card - a porous US border, dissatisfied Mexicans might actually fight to end government corruption & criminal activity, to build a better society, rather than running to Uncle Sugar. This will cost Mexico more than wealth alone.
“Money saved is as good as money earned.”
No, it’s much better because you don’t have to put in ANY LABOR to get it.