[justcomments12]

Empirical evidence: They would denounce citizenship and move to other countries. This happened in France with a wealth tax, which caused high net worth individuals to move to other countries (like Gérard Depardieu). You can see the same thing in other places of Europe, where citizens flock into Monaco, Jersey etc. The US is no different, plenty moved to Singapore, Cambodia, Monaco, Jersey and other places. The same is true for Chinese nationals and others.

Wealth can be used to influence political power, which can be used for good or bad (In the past billionaire Pablo Escobar was overthrowing the Colombian government, funding terror group FARC etc.). So it depends on what the billionaire wants, not democratic process.