The rich aren't Scrooge McDuck or Smaug. They didn't have swimming pools full of cash and gold. They are wealthy because the vast majority of their wealth are investments. They own large portions of companies. Sure they may have an expensive estate or three and a yacht and private jet, but that is s small portion of their wealth. This is actually one of the reasons I dislike a wealth tax.

Most of their wealth isn't money, it's investments. It's not sitting idle, it's being used by whatever they invested in.

Where's the data to back up your assertion about the rich "sit on most of their money"?

I think many of the top tech billionaires have their wealth in company stock (in the case of Jeff Bezos and Steve Ballmer, Bill Gates has diversified away from just MSFT stock, Elon Musk is mostly TSLA and SpaceX)

If the rich actually sit on most of their wealth (all cash - 0% interest, no income, no interest-bearing instruments/bonds, no selling stocks) then they'd pay no taxes on their wealth in the USA. But inflation would hit them hard, especially in the past couple of years.