Re: I note that America...
"Not exactly. They are sending their money through tax havens and may be buying US dollars in those tax havens. I very much doubt they are letting their money actually sit in the US.
Even US billionaires don't do that."
Actually, they do, just not as currency. The richest of the richest know the best place for wealth is in real estate, which by its very nature naturally appreciates due to increasing rarity and cannot be taxed as long as it's simply held. When they need money, they borrow against it and then hold the debt until they die when their heirs can employ a trick called the carryover basis to rebase the assets and dodge capital gains taxes when they sell off some of the assets to pay off the inherited debts. I believe they call that "Tax Planning 101".