So we've gone from "The US not having socialised medicine makes it a reseach powerhouse that the rest of the world has to leech off because of their backwards programs" to "The US has more citizens than other 1st world countries".

Hardly a great argument, but at least the latter actually is "common knowledge".

The original claim was "The United States is subsidizing the medical expenses of the rest of the planet."

When some evidence was provided, you stated that per capita they're only doing 1/3 more than the UK.

The thing is, that original claim that others were arguing with had nothing to do with per capita. The proposition is based on absolute numbers.

And for the larger argument about what current proposals would do to innovation in medical treatments, what we're really talking about is the total amount of research, not per capita -- the latter is a red herring.

The fear is that, if the USA clamps down on healthcare spending, then much of the research that's done in the USA won't continue. And if that's the case, then the pace of improvements in healthcare will slow, and in the long run that's a very bad thing.

That proposition is certainly open to debate. But decomposing the facts into per capita data is a red herring that does nothing to resolve the question one way or another.