It's not talked about that much but precious few FIRE influencers (finfluencers?) live below the median of their area. Let's review.
MMM + wife were making roughly 200k in 2007, which CPI adjusts to 300k today (!!). The much-vaunted MMM household spending target of 25k in 2010 CPI adjusts to about 36k today, plus imputed rent of a house in longmont (2k/mo) is a realistic $60k of income. There's also that rental house they had for a while. That's at or higher than the median household income in Colorado.
Root of Good maxed out an income of roughly 120k in 2011 or 2012, which CPI adjusts to $170k today, in North Carolina. With a spending target of 40k (even today!) and imputed rent of a paid off house in NC (2k/mo minimum) that's a $65k of income. Median household income in NC is $62k.
Go Curry Cracker gives fewer income details but he was making a good tech salary during his working years, their blog income has been pretty higher, and he's had no qualms about adjusting his lifestyle to match his assets.
The Mad Fientist was making a software salary, had no kids, and his wife kept working. WifeFI.
RetireBy40 made tech salary and also had a wife continuing to work.
1500 Days has a recklessly volatile portfolio, got lucky in a lot of ways, and definitely spends a median+ household income.
Millennial-Revolution, despite my distaste for their blog, might be one of the few finfluencers who actually live a true below-median-household-income lifestyle. But they also pay for it - no house, no car, no pets, no possessions that don't fit in a suitcase.
It's the dirty little FIRE secret: everybody brags about their frugality but in reality the most common situation is someone making 3x the median salary of their area, living on 1.1x the median salary, and banking the rest. That's a 60+% savings rate, and provides them with a median standard of living after retiring.
The real genius of the FIRE principles is the demonstrable benefit of making modest lifestyle concessions allowing astute investing that provides a snowball effect far bigger than a layperson would ever suspect. However, to save money you need to make money, the more the better (shocking!).