There are levels to Rich and every one of them should be taxed

Just find everything from their pockets first before you even ask us. Your tax rate is now related to the amount of the country's wealth you have. Counting all the stuff you moved out of country specifically to avoid this. That should actually count against them double to further disincentives doing so.

Maybe even worse in the first few years of the change so it will be extremely difficult for them to move back quickly enough to dodge some of the impact of this.