The trick, I think, is to get control of the entire healthcare system.

Am I correct that the man most adamant about Socialism being a bad thing now wants to nationalize an entire industry? And what Industry do you want the government to seize the means of production next?

Auto prices are soaring...shall we nationalize that next?
Banks? Farms? Factories? Railroads? I'm kidding of course. But do you see the issue here? Republicans, and a lot of Democrats, don't approve of these kind of shenanigans.
we pay about a trillion dollars a year (more) than the rest of the industrialized nations on earth

The reason the US spends more isn't just government spending it's TOTAL spending. It includes our out of pocket expenses and insurance premiums.. Which are exorbitant compared to the rest of the world. But they pay a lot more taxes per capita than we do.
Here is a chart that shows you how little we pay in taxes compared to those other industrialized nations. There are other sites to visit if you want to find out more about that....;)

Are you beginning to grasp how this works? Taxes pay for healthcare in those countries.
Just because you pay your healthcare costs in the form of taxes does not mean they go away.

It does mean that for most people it would go down! But for many it will actually go up. It's based on income so the more you make the more you pay. EXACTLY LIKE MEDICARE!!!!
But if Medicare was expanded to everyone and tied to income it would be flush with cash.

Without bothering to Google anything I'll betcha a donut that our government operated healthcare service (Medicare, Medicaid, and Veterans health care) is larger already than the systems in place in most of those countries. The US is much much bigger than any of these other nations. The numbers are pretty mind boggling.

It can be done but it won't be easy. It'll take majority in the House, a supermajority in the Senate, and a willing president.

If the last two years are any indicator Republicans are set to deliver that to us in 2020.
Good coffee, good weed, and time on my hands...