(Reuters) -Tesla (TSLA) CEO Elon Musk on Wednesday became the first person ever to achieve a net worth of nearly $500 billion, propelled by a rebound in the EV company's shares and surging valuations of the tech entrepreneur's other startups this year. Tesla stock rose more than 1$500.1 billion as of 4:15 p.m. E.T., according to Forbes' billionaires index. Musk's fortunes are tied closely to Tesla, where he held a more than 12.4% stake as of Sep ...