We make very roughly $120k/yr total (military pay is complicated) in a supremely expensive area. That cahrt is great, but for a large and diverse state like CA, it still leaves a lot to be desired. (CA is cheaper then Minnesota? lol) Single family homes in our current town start at about $750/sqft. I recall a study last year that this metropolitan area was in the top 5 least affordable (either for housing, or overall--I can't recall). TL;DR It's really friggin expensive here.
And I feel extremely wealthy. Before this thread, I would have said "upper middle class", but only because to me, upper class is tens or hundreds of millions--extreme wealth (.5%, vs 5%). But I certainly recognize how much we have, and can readily accept that by many definitions, we are upper class. To live with this kind of money, even in a high COL area, and think one is average and middle and not exceptionally ahead of most is staggeringly myopic.
I think rich (5% or 1% or .5%) people can by mustachian. But I think part of doing so would have to be recognizing one's reality. And even if that person is eating the same beans as truly poor person, and washing his own socks, mowing his own lawn, and skipping cable, the fact that he can invest hundreds or thousands of dollars a months while doing so makes all the difference. Living on $20,000 because you make $20,000 is not even in the same ballpark as living on $20,000 because you make $220,000 and want to retire in less than 5 years. Heck, even if you live on $20,000 because you make $120,000 and have $90,000 in credit card debt is still a different animal. You are paying for your past stupidity and for your $20,000 lifestyle, so you're still purchasing a lot more than just the $20k.