Eh most of that "money" is actually leveraged Tesla shares. Tesla shares that are overvalued. If he runs Tesla into the ground it's not actually implausible he goes bankrupt.
Of course for the billionaires "going bankrupt" isn't the same as it is for you an me. He'll still live a life of luxury we can't even imagine, he just won't control as much of the economy as he does now. And he can always scam his true believers out of some money by creating a startup promising to to build robot dolphins or whatever (it doesn't matter he's a hype man) which he'll never deliver and idiots will throw money at him.