Assets - Liabilities = Net Worth. Over $1M and you are a millionaire. It's a standard, simple, and really non controversial thing.
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That's multiple times you've tried to write off your preferred method as non-controversial, despite multiple other people in this very thread saying that's now how they view it.* You've also referred to other methods as 'absurd' and 'clearly' your method is the 'obvious' and 'standard' one. Frankly your dismissal of others is insulting.
Certainly many NW as the defining threshold for a millionaire. Maybe even a majority. But it's not universal, particularly among the broader non-mustachian public.
Consider another view. In many parts of the country even modest homes can approach or exceed a million bucks. People who live there often have home equity in the high six figures with years remaining on their mortgage. On paper their NW shows they have over $1M in assets, but if you ask
them if they consider themselves a millionaire they typically laugh and say no way. Why? Because they don't feel rich, they say they can't move because of their job, they have to car loans on newish cars (also adding to the NW). They can't FIRE because they're not mustachian and their expenses are ~$80k, and they've got three kids, and no clear plan how or if they'll pay for college. In short, they are still living paycheck to paycheck. This kind of situation is disturbingly common in HCOL areas. There's even a popular term for this - paper/house millionaire. As in, a millionaire by net worth but not someone who has a lot of money at the end of the day.
It's not the only way, and there doesn't have to be a consensus - that was the underlying driver for this thread - and that's ok. But please stop telling people that their opinions are absurd and the your definition is the clear, simple, obvious and only acceptable one - and all others are absurd.
*about a dozen posters chimed in to say they personally exclude NW when determining whether someone has hit the millionaire mark. Several others have said it's when whatever metric you choose crosses 7 figures.