Is it possible to learn why USA M.Class gave up power and wealth for decades?

Why SV and beyond, mostly well educated workers with high IQ gave up a lot of the wealth+ power to new elite and old rich? in USA? and where to start reading about it?

Just like Buffett said “There’s class warfare, all right, but it’s my class, the rich class, that’s making war, and we’re winning.”

https://www.goodreads.com/quotes/123058-there-s-class-warfare-all-right-but-it-s-my-class-the

They won against high IQ majority?