In aggregate, the 400 richest billionaires put together only constitutes 4% of the total wealth in America.[1][2]
Even if you assume that power correlates perfectly with wealth, there's not really evidence that billionaires control anywhere near enough money to become a "permanent ruling class".
Well, expand that category to include every billionaire and also everyone above 100 million, as an arbitrary figure that most people will never make throughout their lives. I imagine that percentage will go up immensely.
Two thirds of wealth in America is owned by the bottom 99th percentile, i.e. households with less than $12 million net worth.[1] A near majority of wealth is owned by the 90th-99th percentile, i.e. households with between $1-12 million net worth.
By far the biggest source of wealth inequality is the division between the top and bottom 50th percentile, who have essentially zero wealth. The uber-wealthy may be rich on an individual basis, but in aggregate they still hold constitute significantly less than run-in-the-mill retirees, dentists, and actuaries.
That seems like a confused way of saying that those who are at least millionaires have 80% of the wealth.
It's much easier for a billionaire to hire lobbyists to protect his latest exploitative venture than it is for some dentist to do so. That's why the 1% held 30% of the total thirty years ago and they hold 40% now. That is a dark trend.
Even if you assume that power correlates perfectly with wealth, there's not really evidence that billionaires control anywhere near enough money to become a "permanent ruling class".
[1]https://www.brookings.edu/blog/up-front/2019/06/25/six-facts... [2]https://en.wikipedia.org/wiki/List_of_Americans_by_net_worth