The world's richest man, Elon Musk, has a record wealth as his net worth crosses the $600 billion mark for the first time and approaches $638 billion, according to the Bloomberg Billionaires Index. The move comes after SpaceX achieved a valuation of about $800 billion in an internal share sale that made SpaceX the world's most valuable private company. Musk is the company's founder and CEO. After applying a liquidity discount for private companies, Musk's 42% stake in SpaceX is worth about $317 ...