First of all, the rich are very good at hiding their assets, so good luck trying to steal their money when it's on offshore bank accounts or tied up into physical assets (or perhaps some even tied to bitcoin). Second of all, the best way to make a rich person flee a country (therefore no contribution to the tax pool) is to massively raise their taxes. You see this on an individual level in the United States because each state has discretion on their local tax rates. In fact, the way the US works, even municipalities can create their own tax rate. But what you end up with is the rich leaving highly taxed states for states with lower tax rates. In Europe where the entire country has the same effective tax rate, as I mentioned before, the rich will just shove their assets offshore.