just to try to take the conversation back to what I think was the OP's original question, I was faced with this scenario when I opted to retire at age 62, and DW at age 59. Once I could calculate that we had enough money to cover the premiums and deductibles for the number of years we would need to, before Medicare kicked in, I deemed our work was done.
It's another expense of life. If you can't afford to pay it, because you don't have a big enough nut, then yeah, you better keep working. However, I have known many folks who could pay for it, but somehow it was in their heads that since they never had actually written that check themselves, it just wasn't right to pencil that into their budgets. So rather than earmark the 100k out of their nut, which they could easily do and still fund their retirements, they opted to pay for it with another 4 or 5 years of their lives.
Maybe because I ran my own business, and even though I could run the premiums through the business I still wrote the checks and saw what it costs, I was more able to handle it as a business transaction. Just another thing I had to figure out how to pay for before I considered myself ready to FIRE.
As it turned out, due to some unforeseen circumstances, I was able to live off my after-tax assets, and keep income low enough to get some ACA assistance, but that turned out to be a bit of gravy, not what decided if I could or could not retire.
I think those retiring much younger than I did have a far riskier set of unpredictable variables to deal with, than someone only a few years shy of Medicare.