Sure they could cash out without going through the public market. It's "easy enough" to arrange sales of large numbers of shares in private transactions. For

Sure they could cash out without going through the public market. It's "easy enough" to arrange sales of large numbers of shares in private transactions. For Musk levels of money there's have to be more than a few such arrangements. Depending on the buyer's desire for that stock, it can even be profitable, as they similarly couldn't publicly buy such a large quantity without wild market swings.