You have to tax not just income but wealth. And even if it'll work for only a short while, that's OK. It increases the amount of money available to regular people. Suppose that it turns out that there's no need to wage a war 2 more days, or spend a couple more days sorting IRS forms. Well, that's more cash to something else. It adds up. And after that's paid for, the cash is in the hands of individuals, to spend as they see fit.
The government does kinda tax wealth, any time it creates currency ("printing money") beyond the (I'd guess very small) rate at which it vanishes, e.g. by banknotes getting shredded in the wash, weird computer errors, etc.
(Because when there's more money around, prices and wages go up, and currency-denominated assets like money in bank accounts become less valuable. It's not clear that this does much to the assets in which wealthier people are more invested -- stocks and real estate -- so I'm not arguing that it's a good way of taxing wealth.)
