Adam Bowen and James Monsees, Founders of US e-cigarette startup Juul, have become the world's first e-cigarette billionaires, according to Bloomberg. This comes after Marlboro owner Altria invested $12.8 billion for a 35% stake in Juul, valuing the firm at $38 billion. Bowen and Monsees own stakes of $1.36 billion each in Juul, now more valuable than Elon Musk's SpaceX.