The richest people make their money primarily from capital investment, which has returns proportional to the capital invested, which in the long run is exponent

The richest people make their money primarily from capital investment, which has returns proportional to the capital invested, which in the long run is exponential. Laborers make their money primarily from effort over time, which is linear. So it makes sense for their taxes to be different. Additionally the amount of money someone needs to live comfortably is more or less constant (regional differences apply), so it's less harmful to tax someone with more than that than someone with less. An economist will tell you that a handful of taxes are inherently helpful and getting money is a nice bonus (externalities taxes, some amount of LVT). If you need more money than what you can get through those (and you do) then the least harmful tax is a wealth tax, but those are unpopular and difficult to administrate. Income-based taxes are less efficient but still okay. Sales taxes aren't very good at all.