The rich don’t have much cash
Rich have assets (e.g., stocks in Wall Street, houses, etc.), more than cash. Taxing such non-cash wealth is complicated.
The Pharaonic wealth valuations of the rich come from their assets, not from their cash. Taxing wealth would require buyers in cash. When every rich person is selling, who will buy? At what price? What tax income would be left?
Instead of taxing wealth in cash, it would be more realistic to confiscate the assets. It happened with communist-era nationalizations, and it didn’t end well. It won’t solve the equation of private initiative, individual rights, good jobs, budgets for defense, and funding for the green transition. It may even backfire with serious discontent and revolutions.