even with the puniest of interest rates, you’d still make more than enough just off the interest to live somewhat comfortably

I’d go one step further and assert that wealth compounds and borrowing rates fall with your aggregate wealth. Treasuries are the safest of safe bets, but there are much higher returns to be had with some minimal risk that become accessible when you have large cash reserves and access to cheap credit. Home ownership is a classic example. Save thousands of dollars a year on rent by owning an appreciating asset you get to live in.

You don’t need $100M to make this work. $100k can turn a handsome profit through compound returns on investment. In a stock market that yields 7%/year, you double your money in a decade.