You wouldn’t think this is what a 160-170 IQ looks like but I’ve known too many of them now to think they’d match the TV stereotype. The personality is like an eccentric parody of normal that’s built up from years of trying to be normal, giving up, and making a joke out of it. Where most people order clothes from China, he wears shirts that say HONG KONG in big Chinese letters.
If he were in Singapore he’d probably wear a suit with “Respectable Businessman” spray-painted on the front.
The dark triad character he plays works because it’s insincere and self-aware, where he’s mocking modern people by going further with it than they would, like a clownish caricature. He’s actually not a nihilist at all, he’s extremely idealistic and probably the hardest worker in American media. The Joker is just the character he plays for the ongoing reality TV show. Not that the whole personality is an act (acting 180 degrees opposite your nature is hard to maintain for long), but he’s exaggerating the nihilistic impulses for effect.