Not who he is, but what he is. Granted, these processes of selection, admission, incorporation and assimilation are administered by mere humans and are, therefore, subject to human failings. These concepts are vague and ambiguous enough to accommodate bias and bad will. Still, at least appearances are kept in most cases, and decisions can be challenged in courts. Usually, they are accidents, occurrences absolutely beyond the control of those most affected by them.
Race is such a transcendent parameter, as is gender, familial affiliation, contacts and influence.
And often, belonging to one such club is the prerequisite for joining another. The privatization of state enterprises in most Eastern and Central European countries provided a glaring example of oligarchic machinations. The national wealth was passed into the hands of relatively few, well-connected, individuals, at a ridiculously low price. The nations involved were robbed and their riches either squandered or smuggled abroad. In the affairs of humans, not everything falls neatly into place.