Vanderbilt got his start sailing barges across New York Harbor, and gradually expanded into steamships and railroads. One of his favorite business tactics was to undercut the competition so heavily that they would pay him to stay out of a given market.
He was rough around the edges -- swearing, chewing tobacco -- and never really fit in with New York high society.
His heirs did better, building great mansions along New York's Park Avenue and hob-knobbing with the city's elite. But they spent heavily, and by a 1973 family reunion, not one of the 120 Vanderbilt descendants present was a millionaire.
Source: *Most nominal wealth estimates are from The Wealthy 100 by Michael Klepper and Robert Gunther, and include wealth at time of death, including bequests. Estimates were then calculated as a fraction of the overall economy at time of death by Sam Williamson of Measuring Worth, and then presented in 2013 dollars based on the size of the current U.S. economy. Estimates for Gates and Buffett provided by Wealth-X.
Biographical information from The Wealthy 100 by Michael Klepper and Robert Gunther, Encyclopedia Britannica, and The Prize by Daniel Yergin.