Ah, the old "just make everyone pay 50%+ tax rates and we're covered" trick.
why are you inventing artificially large numbers?
it's not even a trick, just reality: there's no reason to continue to subsidize private insurance purchases if tax dollars are paying for a competing system
we'd also be paying for it by eliminating medicaid and sending any federal subsidies to states for those programs (and, most likely, looking to redirect state tax dollars that pay for state-level medicaid) to the national program. VA also, and whatever insurance govt employees/senators/etc get.
the main "trick" is accepting the need for economy of scale and recognizing some things are much worse on the local level (why insuring 30,000 people gets you much worse negotiating power than insuring 300,000,000 people)