You can still get ACA subsidies if you fall within the income level it's not means tested, they absolutely designed it this way to be gamed. Also qualified distributions from a ROTH IRA are not considered part of modified adjusted gross income.

So do your mega-backdoor ROTH conversion and take out of that and it doesn't count against the insurance-company subsidy.

The subsidies don't help with copays, deductibles, and co-insurance, right? Those can run into the five figures even on a "silver" plan, in a bad year. If someone on the plan gets cancer, congrats, now every year is a bad year.

that's partially true, but... 'retiring' on $100k year is still potentially disastrous if you have a major health issue.

Sure, yeah. My point is mainly that expenses for early retirement in the US have the potential to vary a lot compared to... well, basically any other OECD state, really, mostly due to healthcare. This makes the lower bound for a reasonably-safe early retirement quite a bit higher, such that merely generating enough safe-withdrawal income to live on in a good year isn't enough, even if the markets do exactly as well as you're counting on and that income's steady.

Obamacare subsidies are based on income. You are likely getting subsidies at this level of income. Will it exist for the next 40 years, who knows?

A couple years of serious illness for you or anyone you're responsible for (spouse, children) will still ruin your retirement plans, if you try to retire early on $40,000/yr in income. A "Silver" exchange plan, even if the premium were $0/m, would still expose you to so much financial risk ("max out-of-pocket") that you'd be rolling some not-very-friendly dice, trying to retire early.

What is the max out of pocket number that you are seeing that is so financially ruinous?

My out of pocket maximum is something like $7000/year. That would be painful on $40k/year, but we're talking about someone with a $1M nest egg, so unless you hit the maximum every single year, its not impossible to cover. Spending $47k/year for a couple years instead of $40k isnt going to financially ruin someone with $1M.

My assumption is that a couple (say) would be running with pretty thin margins, even assuming no mortgage interest or rent and modest living, on $40,000 a year and a fairly low CoL area, so losing another $7k (that's per person, right, not the max-out-of-pocket for the whole plan? Or maybe your exchange plans are way better than ours) would be be very painful, at best. A forever-alone hermit living in a rural trailer park might be another story—there are definitely some circumstances I can imagine in which it might be kinda OK to try to retire before Social Security and Medicare kick in on $1m savings, but not ones that involve anything like a normal life.

And sure, you may not be missing payments thanks to the $1m in the bank, but if you start eating that principle too early (=before you're 60ish years old, at a minimum) you might find yourself needing to get a job after being out of the work force for (say) 10 years and while possibly dealing with serious, chronic health problems. I'm not sure how disability works when you haven't worked for a few years due to retiring, and have six-plus figures in the bank still, but my guess would be "it doesn't", until you are, in fact, ruined.