That never stops the typical monarch from taxing the populace to give them more money. Once again your “theory” is 100% counter to actual historical fact. Kings tax, often quite a bit.
A typical taxation level in the modern industrial democracy runs about 50% (it is often masked by complex tax system). Yet we have bridges falling down, a pension plan that is going bankrupt so we fix it with a peasfule invasion of foreign guest-laborers, and we are not in any war we cannot get out of if we wanted to. Show me a similar predicament in any monarchy.