https://finance.yahoo.com/news/takes-middle-class-americas-l...
I think you are missing the point. In most of the US, there simply aren't enough opportunities to make 6M. To make 6M in the first place, you have to be in a high CoL place like SFBA or NYC. Or at least that was the case until very recently.
And once you put roots down in a high CoL place and have a total wealth of 6M, it is much harder to uproot and move somewhere else. Barring maybe a few who came from low CoL areas and still have roots and connections there.
Choosing to live in more expensive parts of the city and for 2.5 times that may open up lots of opportunities, and that's all good. You just are just butting up against the realm where calling yourself middle class becomes silly. People have a weird psychological affinity to self-identifying this way, but "I know a bunch of people who make 10x what I make", isn't really a good argument for it. Having a few million in assets definitely puts you out of the running, which is where you are likely to end up if you have this sort of salary for a while and aren't stupid with it.
Middle class is explicitly not about passive income. If you are living off "safe withdrawal rate", you are wealthy, almost tautologically.
In extreme versions (e.g. some of the FIRE folks) you may be living some version of a "middle class lifestyle", but that's not the same thing. It fundamentally changes the options and opportunities you have.
This person has effectively "won" at life and is far outside of middle class.
I think the 6million is aspirational.
If you have to work a 9-5 for somebody else to survive then you're working class, not middle class.
The traditional American dream was a middle class life: stable career, single income family, house in the suburbs and a nice pension check when you retire.
Fair to point out that that is a bygone era and maybe you do need $6 mill now, but maybe we need a different name than “middle class” to describe it.
But not in the United States.