> I don’t have reason to believe my insurance will suddenly drop coverage when I need it. I don’t think that’s a huge risk.

There's loads of cases, including one in this thread, about people who thought they were covered but weren't. This is really a bad situation to be in if it happens, and it should worry you every time there's an event. After all, the insurance company has direct interest in not covering you.

Now the government does as well, this is true. But those cases, eg in the UK it's talked about a fair bit, tend to be where there's a judgement that a treat is neither not sufficiently tested to be useable, or simply not worth the cost-benefit, eg it's expensive and only buys the patient a few more weeks of life. So it's true what you say, but it's worth considering what the balance of risks is: a healthcare co that has an interest against you every time, and has been shown to fight, or the government, which normally only denies treatment in rare borderline cases.

I'd say a big part of it is particular to US culture: the healtcare cos have been shown to not be that easy to get money out of. Somewhere like Switzerland also has private healthcare, but they don't compete in the same way. Everyone must have insurance, and you won't be paying out of pocket above some limit. The companies are not famous for screwing everyone, and compete to provide extra service (eg hotel-like rooms when you have a kid).