That is literally bullying. especially when those insecurities are something that can not be fixed. You can't excuse bullying because "it's for humor." It's cruel.
But he's not being bullied and being harassed. He's a public figure and he has fuck you money. If he doesn't like people making jokes about him, he can simply shut up, disappear from public space and live comfortable life without ever working again.
And yes, it is indeed because he's a billionaire actively shaping a worse society. Not because it's okay to make fun of impediments when it's on rich people.