Tesla's greatest weakness is also one of its key advantages (TSLA)

Justin Sullivan/Getty Images Tesla is now a bigger carmaker, by market capitalization, than General Motors, Ford, and Fiat Chrysler Automobiles. It's closing in on some hugeglobal players, such as Toyota and Volkswagen. And a near-$60-billion valuation has come while constantly losing money and building a small number of expensive electric cars over 13 years of existence. CEO Elon Musk doesn't want anyone at Tesla to get cocky, so lately he's taken to exhorting the company to remain lean and mea...