If you're rich, you look like a genius by default because you're surrounded by incredibly smart engineers, accountants, lawyers, and marketers. It helps if you have enough brains and charm to know when you're upsetting or charming people - which makes sense for someone trying to advocate their position in front of venture capitalists or boards of directors. A little philanthropy makes you look like a saint. This is Warren Buffett, Steve Jobs, Bill Gates, etc - this is the old myth that the rich are smart and charming in ways that deserve the money.

For a rich person to come across as less capable than their underlings, or completely charmless, therefore requires believing in their own mythology to just do whatever the hell they want while creating legitimate hatred.

Being clinically a narcissist helps with that but I'd also suggest that how you can be ultra-super-mega-incredibly rich these days helps with that because now even merely rich people you need to talk to will play to you same as any other underling (like an accountant, lawyer or engineer who needs the job) and there's nothing stopping you from believing your own mythology.