> "insurance" means there's some chance you're having an adverse event, and a lot of chance you don't

Exactly. Classic insurance is a bet: the insured is betting that something bad will happen (e.g. house burns down), and the insurer is betting that it will be fine.

The problem with health insurance is that the insured will always be correct eventually. The model fundamentally doesn’t work, except if you adjust the parameters of timescale, population, etc. (which tends to be grossly discriminatory except for voluntary behaviors like smoking).