UNTIL RECENTLY Elon Musk had little need to look over his shoulder. He once described competition for Tesla, his electric-vehicle (EV) company, as “the enormous flood of gasoline cars pouring out of the world’s factories every day”, rather than the “small trickle” of other EV-makers. SpaceX, his rocket firm, had so undercut and outwitted the bloated aerospace incumbents that it had developed an almost invincible aura.