@rysiek I'm inclined to argue that an optimal, self-regulating, taxation level might be determined based on criteria such as a percentile, such as applying wealth tax starting from a level that exceeds, the minimum wealth level of the top 5% of wealthy people in a country for a short-to-medium term, or something like 3 standard deviations above the population's average for a long-term approach.
In an ideal world, the idea should be neutralising the wealth-based social stratification, so I'm entirely okay with a system whereby a zillionaire can reduce their wealth tax by making all the poor people around them a little bit richer and thereby nudging the average upwards.