Who pays? It's whoever pays the insurance premiums and the increasingly larger co-pays: usually the employer and the individual.
For Medicare, it's all who have contributed to Social Security and Medicare, although that pot is rapidly running out.
For Medicaid, and of course the insurance premiums for federal, state and local government employees, it's all of us who pay taxes.
I spent 10 years as an accountant for a large HMO (I retired 12 years ago) and I can tell you that medicine nowadays is primarily a high-tech industry, relying more and more on expensive equipment which is outdated in only a few years. I remember a discussion with department heads in the radiology department back in the late 1990's, in which they were complaining about the depreciation recommendations from the American Hospital Association (which, at least at that time, were the standard). Most of their equipment was completely outmoded in half the time recommended by the AHA. I recommended that they petition the administration for a shorter depreciation period and provide the statistics to back it up. As a result, the depreciation period was cut in half--which of course doubled the radiology equipment cost. On the other hand, the former method was completely unrealistic because they were expensing outdated equipment long after it had been replaced.