@nickyttrpg the rich won't leave. Billionaires can already live where-ever they care. They are not all in Pakistan where cost of living is low. They live where they most like to.

Tax them more, the city improves, and the desirability notches up.

The other thing it does, is make their properties more exclusive. High end properties are veblen goods - if only the richliest of the richies can afford the taxes, then the ultimate display of wealth is to own such taxed properties.