I think what this misses is that insurers handle the hassle of dealing with negotiated rates. As an example, if you go to the ER and get a strep test, you might be billed $500, and insurance will pay $7 (as ridiculous as this sounds). If you go at this on your own, they'll probably bill you $100 and tell you they are giving you an 80% discount. With lots of phone calls, you can maybe get them down to $50. This is all…
I tried going without when I switched jobs to an employer that doesn't offer it, but one cleaning as a "cash payer" cost more than the annual premiums to buy insurance privately.