If I recall correctly, he had the x.com domain and tried to rebrand PayPal to X. The board went, "are you a fucking idiot?" and replace him with Peter Thiel.
He's been trying to call stuff "X" since he was an edgy teenager. He just never had the good sense to grow out of it, and he fell ass backward into enough money that we all get to watch him go all "Star Wars kid" over and over again in public.