The biggest asset, aside from being a port on a great location, was the right alliances, and foreign countries being the island being let mostly alone, and you not having valuable resources, plus the desire of the rich in countries around the area to use the island as a tax haven of sorts (and later, as their comfy home away from home).
Yew would have been thrown out of office in a week and some "coup" would have been organized if some big foreign power has special interests in the area and wanted him gone.
And if the island had resources like oil or such, it would have been invaded, occupied, "liberated" by some new traiting politician friendly to the outside, every second year.