I really, really do not understand health insurance. I think there are two ways to look at the general principle: from the individual perspective or the social perspective. As an individual, one pays a certain amount a month so that when one breaks a leg, gets in an accident, gets diabetes or lung cancer or whatever else, one's medical costs are all taken care of. For some people (the ones who get protracted medical conditions, like HIV, cancer, diabetes, or even asthma or allergies), it's a good investment. Their monthly premiums, even through their healthy years, are probably dwarfed by the cost of the care they eventually receive. Others, though, rarely if ever get sick, don't end up with huge diseases, and even with the occasional broken bone or hospital childbirth or whatever, probably end up spending way more in premiums than their medical care is actually worth. It's the chance you take: you're paying to insure yourself against future calamity.
But then there's the social perspective of looking at things, where insurance companies use the income from the young and/or healthy to pay for the radiation treatments, surgeries, etc. of the less healthy. It's sort of a view across, with all money from a given period of time being redistributed to cover everyone, rather than a view forward, where your money goes to cover you at a later point in time. I think this collective perspective is closer to accurately describing the insurance system. Really, insurance is a way of putting oneself in an isolated communistic pot, using the money from those who don't need it (the healthier ones) to cover those who do (the unhealthier ones).
So if we accept the "spread the wealth" principle within the limited scope of the insurance company, why are we so skittish to adopt a more widespread yet philosophically similar approach as a nation? We have already accepted that nonsmokers and healthy eaters are paying for others' lung cancer treatments and heart bypasses (well, assuming those managed to stick with their insurance and not get stranded without coverage for their "preexisting conditions"), so why not remove the bureaucracy and profiteering of the insurance company and make it a national program?