I'd like to see some study of what can we realistically expect after the implementation. It's a very good intention but I mean you can't really expect that we tax the rich and the rich will just sit on their asses saying "oh well, I guess that's my life now"
Edit:
A number of studies, including the one carried out recently by the World Inequality Lab, have shown that such a tax would help to speed up the fight against climate change and inequality
I guess they mean this study?
And yes, it'd be beautiful if all the ultra rich would pay taxes. But unfortunately the ultra rich are more often than not an egomaniacs who will do anything (!) than lower their status (i.e. pay taxes)