I know this might appear foolish, but fighting with a corporation whose incentives are adverse to my own (both on the medical side and the insurance side) makes me a little sick to my stomach.
You're often able to negotiate discounts for cash payment from providers, but back when I had insurance that excluded a pre-existing condition I ran into providers who steadfastly demanded the full list price (under threat of collections). It only takes one of those standing pat on a high 5 or low 6-figure bill to cause you to lose on your "bet".
If you have health insurance (in the US) and you have a catastrophic event, your finances are going to be totally wrecked anyway. You're likely to have to declare bankruptcy unless you are pretty wealthy. At least, that's how it's gone with every friend and family member of mine that had to navigate such an event. That's on top of the painful nightmare that is dealing with insurance company claims (which, to add insult to injury, you have to do when you're injured or sick).
The premiums are also so high that I'm very far from convinced that holding an actual health insurance policy is a better option than putting that premium money into an emergency fund.
I got $300,000 in coverage for a catastrophic event and wound up paying $ 3,100.
But I did have good insurance with United Healthcare.
So even with a (single) catastrophic event just paying yourself might save you money still (which seems insane to me).
I'm happy with the ROI I've had with my insurance premiums over my life. I haven't had a catastrophic event but I've certainly had reasonably sizable claims. If I'd invested the last 20+ years of premium expense (about $400K to date) and had no claims I'd have a ton more money, but not enough to cover a catastrophic event later in life. The principal would also have been completely wiped-out a couple of times when I did have claims, however.
I pay the premiums because I'm not comfortable holding bets on both the market and on my health. I'm also unwilling to consider bankruptcy as a morally / socially acceptable solution.
This mixed socialized and capitalist "system" we've allowed to grow up feels like the worst possible one. Healthcare and health insurance expense are a mechanism to extract value from the middle class (i.e. everyone who has money but isn't wealthy enough to buy their way out of the "system").
My preference would be for a fully socialized system, built primarily around protection for catastrophic loss, where everyone contributes w/ no opting-out permitted.
Failing that I'll grudgingly take a fully capitalist system where people who can't afford to pay are left to fend for charity or die.
What we've got is a mix of the worst parts of both.
I had quite a few not-bills of the sort you see there totaling more than a few hundred thousand. Insurance coverage did work in my case.
How many big medical systems/districts in your region can you run up a balance until none will serve you, except through the E.D.?
As to the why, it's because I switched jobs and got my regular labs done and apparently was between coverage that week... they tried to charge me a large multiple of what they charged insurance for the same labs, so I refused to pay.
I also had several bills that were never paid from a week long hospital stay in my mid 30's... Most of them got paid if they'd agree to reasonable payments or settle for lower amounts when I had the money (tax return time, bonus, side work). After 7 years, they were all off my credit and I stopped bothering...