Even that is subject to shenanigans... above a certain level of wealth the overhead of establishing companies, tax residencies, and complex debt arrangements become a rounding error.
Some of the mechanisms are loopholes, that might be closed l. But many start to interact with international business regulations that exist for considered reasons, and are harder to change even if it is serving as a loophole.
You end up with only the small wealth (one lifetime as a skilled professional) group getting caught
Sanction them and their companies. Sanction countries that accept these anti-society misanthropes. Bar them from the US and any territories, encourage our allies to bar them as well. Investigate those companies for crimes to the full extent of the law.
Nobody needs these billionaires; we can create new billionaires and new products. They think they bring some sort of ultra speciality but in reality they are doing something millions want to do and their monopolistic success is preventing others from succeeding; knocking these giants down makes rooms for new businesses and products. This is the entire thrust of a capitalistic economy.