In the affairs of humans, not everything falls neatly into place. Take money, for instance. Is it an inherent parameter or an expressly transcendent one? Making money indicates the existence of some merit, some inherent advantageous traits of the money-making individual. To make money consistently, a person needs to be diligent, resilient, hard working, to prevail and overcome hardships, to be far sighted and to possess a host of other - universally acclaimed - traits. On the other hand, is it fair when someone who made his fortune through corruption, inheritance, or luck - be preferred to a poor genius? That is a contentious issue. In the USA money talks.
Being possessed of money means being virtuous and meritorious. To preserve a fortune inherited is as difficult a task as to make it in the first place, the thinking goes.
Thus, the source of the money is secondary.
An oligarchy tends to have long term devastating economic effects.
The reason is that the best and the brightest - when shut out by the members of the ruling elites - emigrate. In a country where one's job is determined by his family connections or by influence peddling - those best fit to do the job are likely to be disappointed, then disgusted and then to leave the place altogether.
This is the phenomenon known as "Brain Drain". It is one of the biggest migratory tidal waves in human history.
Capable, well-trained, educated, young people leave their oligarchic, arbitrary, influence peddling societies and migrate to less arbitrary meritocracies (mostly to be found in what is collectively known as "The West").
This is colonialism of the worst kind. The mercantilist definition of a colony is a territory which exports raw materials only to re-import them in the form of finished products. The Brain drain is exactly that: the poorer countries are exporting raw brains and buying back the finished products masterminded, invented and manufactured by theses brains.
Yet, while in classical colonialism, the colony at least received some recompense for its goods - here the poor country is actually the poorer for its exports. The bright young people who depart (most of them never to return) carry with them an investment of the scarce resources of their homeland - and award it to their new, much richer, host countries. This is an absurd situation, a subsidy granted reluctantly by the poor to the rich. This is also one of the largest capital transfers (really capital flight) in history.
Some poor countries understood these basic, unpleasant, facts of life. They extracted an "education fee" from those emigrating. This fee was supposed to, at least partially, recapture the costs of educating and training the immigrants. Romania and the USSR imposed such levies on Jews emigrating to Israel in the 1970s. Others despairingly regard the brain drain as a natural catastrophe. Very few countries are trying to tackle the fundamental, structural and philosophical flaws of the system, the roots of the disenchantment of those who leave.