I get the impression that human beings in rich countries spend so much money on health care not because it provides them with health, but because it alleviates their fear of death.
Following this logic, the foremost expenditures in health care are a) mostly preventable diseases that require interventions of surgery or constant life long treatment from pharmaceuticals (diabetes or heart disease, lung cancer, etc), that could be avoided entirely by patients taking some initiative on lifestyle choices with healthier diets and exercise and not smoking or drinking excessively, all of which no doubt their doctors will advise them of repeatedly over a lifetime or b) terminal illnesses or episodes that require extremely expensive interventions to extend life a few extra days or months in most cases.
Most of the latter expense could be removed if people took steps to understand the limits of modern medicine by talking with their doctors ahead of time, assembling a living will, and informing their loved ones (or at least their immediate family) of their wishes or the location of said living will in the event of a tragic illness or accident. The reason we don't do most of that is that people tend to avoid thinking of their mortality, or especially that of their friends and families. We instead expect medical professionals to spare us the pain of death in our lives.
To a certain extent this is an entirely reasonable reaction. Modern science and medicine has come up with vaccinations, antibiotics, and advanced surgical techniques (organ transplants for example), and large medical corporations will market these surgical departments and, especially, pharmaceutical treatments that can alleviate all manner of health concerns. Got high cholesterol, take this pill. And so on. The modern consumer sees that death is no longer a daily concern where it might have been much more present barely a hundred years ago with much higher rates of death during pregnancy or delivery, infant and child mortality, accident rates, and various dread diseases that were far more common. Plague used to be a common occurrence for some cities to have to manage. Now we get common colds that still spread around but, for the most part, epidemics are rare.
I think this suggests that human societies used religion far more extensively to deal with death and fear of such and may explain some of the decline or changes in religious purposes (such as prosperity gospels), but I also think it explains a chunk of the run up in health care expenses across the globe. If fear of death is an immediate and daily concept, religion is a far cheaper and immediate way to service those fears through its promises of immortality or reunification with loved ones, and its use of ritual to balance and order daily lives. If death is a distant, far away concept, then we will look to the things that appear to have caused that change (from the more frequent and thus "natural" state of man) to save us when it does occur.
There are a myriad of other causal explanations for health care expenses (third party payment, first dollar health care coverage, etc), but this one would be fascinating to examine.