He's a plagiarist, a fraud: he claims other's work as his own, and that goes from extremely petty to very large lies. From Fraudulently claiming he's good at "Path Of Exile" to him being Tesla's designer, to him having designed the SpaceX rocket engines.

In all cases research has found: he's lying. He has essentially no technical contributions, not even to his original firm, X (the bank).

Him claiming otherwise makes him a fraud, and a plagiarist.