Health insurance against people's will does alter who they are. And as for quality or content, you're talking about schizophrenics who have zero quality of life, and the content of life consists of eating out of garbage cans and screaming at strangers in the worst cases.
Schizophrenics and others with severe mental illness have no will; the illness controls them they don't control the illness. You can't do something against someone's will who has no will.
Forcing health insurance on people against their will is, on the other hand, morally right according to you.
So you implied argument is: as long as someone has no will, they should be left to their own devices. But if they have a will, they need to be controlled and dominated.
Well, first of all, I didn't say that I was for imposition of health care; you assumed that. I simply said they are not comparable.
However, who are you to declare that someone with schizophrenia (which, by the way, is not only on a gradient but also comes in a number of significantly different forms) has no will? It is not that simple. You assume neurotypicality to be "will" and non-neurotypicality to equate to non-will, but there are many shades of grey in any illness, schizophrenia included. There has to be a balance struck between allowing the individual their rights and assisting them in getting to a place of agency in their own life.
I am not against legally-mandatory psychiatric commitment for those who are dangerous to themselves and others, but it needs to be done in a way that is first and foremost respectful of the rights and wellbeing of the individual. Each person must be interviewed, diagnosed, and treated on an individual basis with the goal of attaining ability to live a self-directed and personally fulfilling life. I do not think it is necessarily a good idea to characterize all people with schizophrenia as "ticking time bombs" - episodes of psychosis can still occur even when they are on medication. I use the phrasing "people with schizophrenia" (person-centered language) precisely because each illness will be as unique as each individual, and everyone deserves to be treated as such. We cannot classify all people with schizophrenia as time bombs yelling obscenities in the streets.
Regardless, as for the real issue: it's interesting you mention health care because we might have far less mentally ill people on the street if we had the resources to provide for them, something that universal health care would help account for. What many people do not understand is that optional health care tends to drive up individual costs, because huge amounts of money are wasted by people being shuffled through the wrong areas of the healthcare system because they do not have the up-front money to pay for appropriate care, or, worse, people who choose to opt out of healthcare and then get seriously ill and seek care, placing the financial burden of their illness on taxpayers. These are not my personal views but simply established fact based on the working of the system.
In the case of the mentally ill, the way health care is handled now, it's generally only mentally ill people with affluent family who support them that get treatment, and hospitals and ERs are clogged with mentally ill people who lack resources because they have nowhere else to go - except hospitals and ERs are acute medical care facilities and are not the right places for people with chronic mental illness. The United States government does not provide suitable medical facilities for the mentally ill; public mental health is severely underfunded in many states and is completely dismantled in others, like mine. Paradoxically, the reliance of the mentally ill on hospitals (which are expensive) eats away at money that could otherwise be used to provide appropriate treatment and care facilities. But you can't ask them to not seek treatment when treatment is what they need. The government needs to suck up the start-up cost and provide appropriate mental health facilities, and then it will reap the rewards in terms of having to pay for less legal control of the mentally ill on the streets and having to pay for less acute medical treatment of the mentally ill in hospitals. But that requires people to put money up front, of course, and in a profit-driven economy (as opposed to quality-of-life-driven) that's unlikely to happen.
In some ways, I think mingularity is absolutely right that this is a failure of society to desire and expect something (treatment and social integration of the mentally ill) but not allocate the resources to that area to be able to achieve it.