He might want to ask Norway how their wealth taxes worked out:

"The recent wealth tax increase in Norway, which was expected to bring an additional $146 million in yearly tax revenue, led to a significant loss of tax revenue as billionaires worth $54 billion left the country, resulting in a loss of $594 million in annual tax revenue.

This outcome highlights the unintended consequences of the tax policy, as the exodus of wealthy individuals not only reduced the anticipated revenue but also led to a net decrease of $448 million.

The situation has been described as a failure of the wealth tax hike, with Norway losing several billion NOK in tax revenue due to this emigration."