The purpose of education for the philosopher King is to endow the King with knowledge and intelligence necessary to rule wisely. This is important as political rule requires knowledge to be successful.
Philosopher Kings have achieved success as they rule wisely and understand how to use power. As a result, they have been able to chart a positive path for their people.
These principles have certainly assisted us in the choice of leaders. Advanced democracies often vote for enlightened leaders that are able to lead the country during periods of crisis. An example is Abraham Lincoln