Elitism stems from two very human traits: the ability of people to overestimate how smart they are, and their instinct for self-preservation. In all political systems, and pretty much every instituion ever made by humans, the governing elite has shown an ability to over-estimate its talents (as being the best for the job of governing) and accordingly give itself unusual leeway in creating and interpreting the rules in favor of staying in charge.
In politics as usual modern democracies have struck a balance between elitism and populism, wherein the elite retain the power, and the electorate retains the right to throw the bums out when the current government becomes either too corrupt or inept (or both). Elitism based on wealth as the main criteria is also known as plutocracy, elitism based on perceived merit has been called a technocracy or the intelligentia. All forms of elitism have been criticized from the populist point of view in that the elite typically fails to deliver public policy that benefits the public at large rather than themselves. Confucianism is a political philosophy based on an elitism of the public sector and a technocrat is the later-day variation, of a civil servant who governs well inspite of the current spate of elected representatives.