Musk, however, said in a tweet that he had "never written or said this" and that Vance's book was "not independently fact-checked" and should be taken "[with] a grain of salt." He later added that the claim was "BS & hurtful" and that another quote used in the piece — in which Musk describes himself as a "samurai" — was also incorrect. The Washington Post describes the quotation as coming from "an anonymous Tesla employee recalling an email from Musk" — a somewhat tenuous line of attribution.

The Post's presentation (as part of a list of the book's "22 most memorable quotes") does not suggest that Vance himself ever saw the email, but the description of the book describes it as written with "with exclusive access to Musk, his family and friends." Vance reportedly spent 30 hours in conversation with Musk, and interviewed 300 people to write the book — a level of thoroughness that does not suggest bad fact-checking.

Whether the quotation is accurate or not it spread like wildfire online, mostly because it fits peoples' image of the tech CEO as a ruthless and fanatical figure, oblivious to what most of us consider regular human emotions. Apple CEO Steve Jobs arguably created the stereotype and Musk is carrying on his legacy. Another quotation published by the Post captures the PayPal founder musing over his love life: "I would like to allocate more time to dating, though. I need to find a girlfriend [...] How much time does a woman want a week? Maybe 10 hours? That’s kind of the minimum? I don’t know." There's been no refutation of this particular line.

Update May 12th, 6:00AM ET: Updated to include new tweets from Elon Musk.