Alternatively, the royals will just loot the sovereign wealth fund and flee the country.
Sovereign wealth funds in third-world countries don't tend to last long. Nauru would still be one if the richest countries on Earth except that the sovereign wealth fund somehow found its way into the pockets of the people tasked with looking after the sovereign wealth fund.
I also thought of Nauru. Seems the island center is chewed-up former phosphate mines and the islanders have nothing to show for it. Australia briefly (?) tried to relocate some unwanted refugees there. Not much to say for the place anymore.
Sovereign wealth funds in third-world countries don't tend to last long. Nauru would still be one if the richest countries on Earth except that the sovereign wealth fund somehow found its way into the pockets of the people tasked with looking after the sovereign wealth fund.