No one is taxing wealth, though. They are taxing income. Please be aware of the fact these are different, that such wealth can be accumulated despite steep income taxes, and that even if such taxes are desirable NYC is not necessarily the jurisdiction which (a) is able to collect those funds, or (b) deserves to have them.

Social engineering schemes at the city level have meaningful constraints.

Does that 30% wealth necessarily belong to NYC? It might not have been acquired there.