The "necessary, but not sufficient" is unintuitive to most people. Billionaires who come from working class families are almost unheard of, but probably more th

The "necessary, but not sufficient" is unintuitive to most people. Billionaires who come from working class families are almost unheard of, but probably more than half the self made (for a definition, something like multiplied familial investments by at least 100x maybe?) billionaires come from upper middle class families. I wonder if they are actually more likely to come from upper middle class (where parents are highly paid professionals) than the proper idle rich or even CEOs and company founders...