Right, so his true wealth isn't that liquid ordinarily, and he'd get a lot poorer if people started selling those stocks. His enormous wealth could be just that

Right, so his true wealth isn't that liquid ordinarily, and he'd get a lot poorer if people started selling those stocks. His enormous wealth could be just that he's a beneficiary of the 'Stonks go up' stimulus/QE driven world we live in, and Elon Musk might just be one giant malinvestment, to be revealed if the market was actually 'allowed' to fail by the Fed, with an end to artificially cheap credit and cheap margin debt. Or he's truly onto something and he really is that valuable... I know which one I'd pick.