What are some advantages to an oligarchic form of government

In an oligarchy the power is in the hands of a small group of people who belong to a privileged class. In ancient times it was the ruling caste that possessed the power monopoly: a hereditary social grouping that is separated from the rest of society by religion, kinship, economic status, prestige and sometimes even language. Such elites tend to exercise power in the interest of their own caste.  

In an oligarchic form of government, the validity of the laws is based on the discretion (group willingness) of this closed elite. It is one of the five forms of state described by Plato, who identifies the oligarchy as the "bad" variant of aristocracy because the oligarchy only aims at favoring its own class.

Given this definition and the way in which they favor their social group, the oligarchies have few positive attributes regarding society in general and the state as a common whole. However, an advantage that these governments may have lies in the continuity of policies that, although they are aimed at favoring the elite, provide security to the remaining nations regarding their relations with the government, as well as with respect to the measures they will carry out. In this way, they provide stability and, if their policies are favorable to free trade, they can encourage foreign investments.