These amounts of money is not actual money but military equipment that already exists in american warehouses, often overpriced(priced as new, even though they are about to be decommissioned). The alternative is to use missiles and tanks as payment for doctors.

The cost is that eventually, the american military will need to replace that equipment by buying new stuff. But thats a different conversation.

Agreed. You would then have even more money to spend on defeating russia: https://www.citizen.org/news/fact-check-medicare-for-all-would-save-the-u-s-trillions-public-option-would-leave-millions-uninsured-not-garner-savings/