The average billionaire on The Forbes 400 ranking of America’s richest people is 70 years old, and 23 of the list’s members are in their 90s, including land and lumber mogul Archie Aldis Emmerson, who is the oldest, at 96. But a select few lucky billionaires have managed to amass at least $3.8 billion—this year’s record-breaking minimum net worth—while still relatively young.
