If you accept cancer as a death sentence, you're an idiot. I had cancer at age 41. If I left it untreated, sure I'd be dead, probably by age 43. But I'm not an idiot, I had good health insurance, I was treated, and now that health event is over twenty years in the past.

Had I self-funded with a (non-existent) nest egg, I would still be in debt over $600k. Instead, my insurance had to deal with that...

600k once in 40 years is cheap compared to the total cost of insurance, especially when you consider the compound interest you could have made on premiums not paid, plus with the freedom to get cancer care cheaper someplace privately outside the US.

Your insurance company got the last laugh by a long shot. A typical family on insurance would pay $600,000 (between their take-home and the reduced wages paid by employers to cover insurance) in just 25 years, and that's before considering the opportunity cost of lost investments/yield.

While I won’t argue insurance wasn’t overall beneficial in your case…

There is no way that $600,000 is the cash price for cancer treatment (especially 20 years ago, but also today).

The average cost of cancer treatment is $150k [1], and lower with cash price + shopping.

[1] https://treatcancer.com/blog/cost-of-cancer/