I have to respond to “with at a 50% wealthtax over 20 million euros” because that is the easy answer
Europe already has a lot of experience with taxing the ultra wealthy
In 1990, about a dozen European countries had a wealth tax, but by 2019, all but three had eliminated the tax because of the difficulties and costs associated with both design and enforcement.[6][7]
https://en.wikipedia.org/wiki/Wealth_tax#In_practice
Normally progressives like to point to Europe for policy success. Not this time. The experiment with the wealth tax in Europe was a failure in many countries. France’s wealth tax contributed to the exodus of an estimated 42,000 millionaires between 2000 and 2012, among other problems. Only last year, French president Emmanuel Macron killed it.
In 1990, twelve countries in Europe had a wealth tax. Today, there are only three: Norway, Spain, and Switzerland. According to reports by the OECD and others, there were some clear themes with the policy: it was expensive to administer, it was hard on people with lots of assets but little cash, it distorted saving and investment decisions, it pushed the rich and their money out of the taxing countries—and, perhaps worst of all, it didn’t raise much revenue.
Paris (AFP) – Bernard Arnault, the billionaire boss of the world’s biggest luxury conglomerate LVMH, has picked a fight with the French government by suggesting that companies could flee France for the United States to escape a planned tax hike.
And it’s hard because there will always be another country that wants rich people
tbf they got a pretty weak lineup iirc