Barely a week after they bid adieu during a collegial meeting in the Oval Office, Pres. Donald Trump and Tesla CEO Elon Musk have launched what has rapidly escalated into an all-out war of words, amplified by their individual social media outlets. The feud has already left Tesla lurching, nervous shareholders fueling the automaker’s biggest one-day loss ever. But Musk appears positioned to do some damage of his own.