How is it win-win for everyone when one person pays for another person's healthcare? There might be overall good effects, but it's clearly win-lose in its basic transaction.
In a public system the federal government would pay. Since federal government's ability to pay is only artificially restricted by Congress, there should be no problem affording it financially. In other words, it's not citizens paying out of their pockets for other people's care. It's fed paying. Worst problem would be potential inflation. Likely because system would be cheaper overall it would have immediate economic boost. Like putting extra 5k in everyone's pockets.