"It's like being dropped into a zone of shocking competence." Marc Andreessen on working at one of Elon Musk’s companies: "Everybody is like ultra competent... If they're not, Elon sniffs it out and fires them." "The best engineers in the world want to work for him because he's the one CEO like this who's able to work with them as a peer." "So he just has this incredible positive selection where the smartest people in the world want to work for him and anybody who can't cut it gets…