He got the details wrong, but the important part right. They live off of loans and either let the interest ride or only sell enough assets to pay the interest. When they die, their heirs can sell as much as is needed to pay the loan tax free because the basis is reset to the current value of the assets when they are inherited.
This isn't the only thing they do, but it is one part of it
It used to be that when people talked about hypersonic missiles it was understood to mean hypersonic cruise missile, something that could hug terrain and maneuver. Then Russia and China came out with "hypersonic missiles" that were just ballistic with maybe some minor maneuverability so the term doesn't mean anything until you dig deeper.