(The article basically asks why there are so very few billionaires in the U.S. - when any family that got decently rich 50 or 100 years ago, then had enough brains to park their money in an index fund, would end up as billionaires today.)<p>My take: Billionaires are just pretty-bright, really-aggressive people who also got lucky for a while. Imagining that their <i>families</i> somehow inherit their smarts and luck is just plain delusional. If you read a bit of history - that sort of belief is the foundation of the whole "kings, princes, dukes, ..., gentlemen" social hierarchy of long-ago Europe. And history records just how reliably (and how badly) the "$Descendant of $Great with also be $Great" theory has proved itself wrong.