We don't use the dollar, but I take your point: the royal family are clever to have lasted so long.
In the end, the taxpayers are forced to keep ensure you and your heirs remain billionaires without having to do more than wave your hand at a public appearances and attempt to stay out of the tabloids.
(I prefer using dollars because it has a more vague meaning of currency whereas the word “pound” has 30 meanings and uses on Wordnik. The English language sucks, but I digress.)