From X.com to X Corp., the letter X holds "great sentimental value" to billionaire Elon Musk, ... to pay your rent, to book appointments with your doctor and even to pay fines," said Vance.

The letter X is both rich with connotations and ambiguous, ... and open-ended,” as Jimmy Soni wrote in his book The Founders. But X.com apparently reminded people too much of porn.