Statistically, many "average" upper middle class people are very able to become low tier multimillionaires through a well educated upbringing and a good job, and good financial decisions over a long period of time.

But many of those people take their entire lives to go from "pretty well off" to "technically a multi millionaire, after many years of hard work, and planning" and got there from very reasonable expectations.

Now a billionaire is literally about a thousand* times richer than any of those people. We're talking "I literally make a difference in elections without anyone knowing my name" rich.

Maybe this is a good example of how rich billionaires don't need to be. The mere fact some people can't even imagine the difference between a factor of a literal thousand* (how ironic of me).