This seems to ignore the fundamental reason that billionaires don't pay taxes. It's not that governments don't try to tax billionaires. It's that they're able to avoid claiming income when they make money. But following this reasoning, they would likely develop ways to avoid claiming wealth as well. Consider, for example, Warren Buffet's own example of his California properties which have a taxable value well below their realistic market value. Similar sleight of hand would likely be employed (with a few strategically positioned lobbyists having lunch with legislative committees) in order to allow billionaires to minimize their taxable wealth.
The more practical approach, as I understand it, is a tax on securitization of assets: whenever someone takes out a loan against an asset for expenses (which is common among the wealthy to avoid realizing gains), a tax is assessed on the loan value. This makes the tax harder to avoid because it is assessed closer to the actual use of money, which is a documented event. While this may affect the second mortgage and "auto loan" industry, weakening predatory finance doesn't seem like that much of a bad thing.