we can indeed tax the rich

Admittedly, America already does. Iirc the top 10% pay about 70% of American personal tax revenue.

Revenue from it has climbed

Yes, the tax isn't so bad that it is immediately revenue negative, that'd be comically bad. The concern is that wealthy folks pay taxes in a lot of ways beyond a single wealth tax and when they leave, even though the wealth tax revenue might still increase, the overall tax base decreases.

You might keep reading:

Around 40% of emigrants are business owners, according to Princeton researcher Christine Blandhol, who estimates, opens new tab the latest tax changes will cut Norway’s output by 1.3% over the long run. Others find the tax hampers firms' performance, opens new tab. A wealth levy is especially painful for startup founders, who pay on capital long before profits arrive. Are Traasdahl left Norway in 2000 to market Europe’s mobile technology in the U.S., later founding and selling several tech firms including the app now known as iHeartRadio. "There’s no chance I would have been able to build in Norway what I built in the United States," he said. Norway has one of Europe’s lowest levels of venture capital as a share of GDP – at half that of Sweden's and far behind the U.S., OECD data shows.