The world’s first billionaire was oil tycoon John David Rockefeller Sr. He achieved the first billionaire status in 1916 as owner of Standard Oil. Rockefeller was able to amass such a large fortune as a self-made man because of his monopoly on the oil business—he owned 90% of the worldwide supply of oil refineries, in addition to owning one-third of the world’s oil wells. By 1911, Standard Oil was found to be in violation of antitrust laws by the US Supreme Court and was broken down into 30 separate companies. It is estimated that Rockefeller would be worth approximately the equivalent of $400 billion US Dollars (USD) if his fortune was adjusted for 21st century inflation rates.
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