I'm not doing FIRE, I have children and just live below my means. I'm hoping to retire around 55 assuming the AI bubble doesn't nuke everyones portfolio.
There are various ways to look at numbers but my thumb rule is 4% inflation 9% growth keeps you perennially happy with some choppy years of course. 4% inflation 9% growth implies you can withdraw 4-5% every year and still have equivalent portfolio in inflated money.
Five years ago I paid for “market rate“ insurance through my business for my family because we did not qualify for ACA subsidies. The cost was about $40,000 per year.