It happened in Norway and is happening in the UK and California. Unfortunately the effect seems to be real, although IMO it may not be the taxes themselves as much as the increasingly hostile attitude towards wealth, which may cause the wealthy concern about unknown future actions.

Without a global wealth tax (which seems impossible to coordinate) then I don’t see a good solution if the goal is to extract excess wealth from UHNW individuals. This is why a Georgist land value tax scheme is probably better; it levels out real estate speculation, which is a favorite parking lot for excess wealth and which has terrible side effects. Over time this will level out wealth inequality slightly, while forcing unproductive (rent seeking) wealth into the market.

I’m in favor of a single tax (just LVT), which economists say is possible, but if you must then you could also tax stock/bond profits (trading, dividends, coupons) at a higher rate. This may be a bad idea though if it pushes investors over to foreign markets.