Well, many of them sure, but not all of them. For example, Bill Gates has his wealth distributed across a wide range of investments, which means that Gates' abi

Well, many of them sure, but not all of them. For example, Bill Gates has his wealth distributed across a wide range of investments, which means that Gates' ability to turn his wealth into cash is much much greater than Jeff's. As for the theoretical part, billionaires with all of their wealth tied up in a single company generally only have access to billionaire kind of money through loans with incredibly generous terms that they pay back by selling a bit of their stocks every year.