Ultimately the problem with a private healthcare system is there is no incentive to provide appropriate affordable healthcare and every incentive to divide, marginalize, and monopolize markets in the aim of driving down competition and driving up profits.

Now that the US healthcare industry has grown so rich and powerful it can lobby and win against any serious political efforts to either increase market competition or socialise healthcare. I.don't. Know how you could politically fix a system that is essentially "every man for himself" the incentive for corruption is far too high when payouts equal political power.

I doubt the US is subsidizing medical research as much as you'd think. The Pharmaceutical industry for example is very profitable compared to other industries. A socialised healthcare service would enable more competitive prices eating into industry profits for these products due to market scale like we see in the UK due to the buying power of the NHS.

"Among the largest 25 companies, annual average profit margin fluctuated between 15 and 20 percent. For comparison, the annual average profit margin across non-drug companies among the largest 500 globally fluctuated between 4 and 9 percent."

https://www.gao.gov/mobile/products/gao-18-40