All true. But this is on a linear scale. Worth noting that wealth aggregates exponentially. Which is to say, getting from $0 to $1M is far more difficult than getting from $1M to $2M, thanks to our financial system's method of compounding returns on investment over time.

The cost of one's basic living needs heavily weigh down one's ability to aggregate wealth when one is poor. But basic living costs are trivial to someone who is rich. Same with one's ability to leverage borrowing power. It is very easy to become a billionaire if you can get ahold of a billion dollars in credit. And much of the real value of modern billionaires is measured in their credit-worthiness rather than their real liquidity. Elon Musk is a great example - a guy whose billionaire status is almost entirely bound up in how his car company and his social media company and his aerospace company are valued.

The speculative valuation of these firms is driven by the availability of lending. That's why Tesla, a company that produces less than 1M vehicles/year is valued at twice the market cap of Toyota, a company that produces over 10M vehicles/year.

TL;DR; The millionaire/billionaire distinction isn't linear. It is exponential and heavily speculative. Real utility value isn't what gets measured. And so the distinction between a millionaire and a billionaire is far more about one's ability to borrow money than one's actual accumulated assets.