In the first Forbes 400 , oil was the source of 22.8 percent of the fortunes, manufacturing 15.3 percent, finance 9 percent, and technology 3 percent. By 2006 oil had fallen to 8.5 percent and manufacturing to 8.5 percent. Technology, however, had risen to 11.75 percent and finance to an extraordinary 24.5 percent.
And get this:
The average net worth in 2006 of Forbes 400 members without a college degree was $5.96 billion; those with a degree averaged $3.14 billion. Four of the five richest Americans — Bill Gates, casino owner Sheldon Adelson, Oracle’s Larry Ellison, and Microsoft cofounder Paul Allen…– are college dropouts.
Both are from the quite engaging All the Money in the World — How the Forbes 400 Make — And Spend — Their Fortunes, by Peter W. Bernstein and Annalyn Swan.