Elon Musk may soon become the first person with a net worth of $300 billion. The Tesla CEO and world's richest man added more than $36 billion to his fortune on Monday after the automaker's shares spiked 12.7% following the announcement that Hertz is ordering 100,000 vehicles to build out its electric vehicle rental fleet by the end of 2022. The single-day growth of his fortune was largest in the history of the Bloomberg Billionaires Index and equal to the net worth of the 34th rich...