How much savings from entitlements would accrue?
How many fewer welfare, and related, workers would be needed?
How much would be saved by the health sector?
How much would the schools not need to spend?
How many unemployed Americans would be hired to replace the lost illegal workers?
How much stress would be removed from electrical, water, sewerage, and trash infrastructure?
How much fuel needs—all fuels—would be eliminated if they weren’t here to use it?
How much would be saved by law enforcement, including the courts & jails?
How would all those factor in against the cost?
How much is reduced crime worth?
Would it have been cheaper to not fight WWII, and just let Japan have the west coast; and why was that not a factor in whether or not to fight? How is this invasion different, that cost is become the primary factor?
The savings from schools, prisons, welfare and such plus opening millions of jobs for actual Americans would be a huge boost for the country.