They did not in fact diagnose anything, "mental illness" is not a specific condition in the DSM. You'd have a valid point if they confidently stated he had bipolar disorder or something.
Sure, it's not, but it's a term used to describe a wide collection of conditions that are in the DSM.
In some ways, asserting that someone has "a mental illness" is worse than saying they have something specific, like bipolar disorder. It's lazy and dehumanizing, and takes away their agency.
Yes, buy NPD *is* in the DSM. While I'm not a mental health professional (read: I can't diagnose with any authority), I would still say that Mullenweg consistenly exhubits many / most of the symptoms of classic NPD.
