R$D and invest and hit the books 

Rank  Name      Net Worth   Age Country/Territory   Source  Industry
1   Elon Musk   $839 B     54  United States   Tesla, SpaceX   Technology
2   Larry Page  $257 B     52  United States   Google  Technology
3   Sergey Brin $237 B     52  United States   Google  Technology
4   Jeff Bezos  $224 B     62  United States   Amazon  Technology
5   Mark Zuckerberg $222 B  41  United States   Facebook    Technology
6   Larry Ellison   $190 B  81  United States   Oracle  Technology
7   Bernard Arnault & family    $171 B  77  France  LVMH    Fashion & Retail
8   Jensen Huang    $154 B  63  United States   Semiconductors  Technology
9   Warren Buffett  $149 B  95  United States   Berkshire Hathaway  Finance & Investments