Also it is not one of the ruling pillars. Rather, it is merely taking an opinion which is binding in some cases and not binding in others. However, Shura is a divine rule. Thus, it is forbidden to take the beliefs and civilization of the West. Democracy is a part of the Western civilization which emanates from the Capitalist belief of separation of belief from life.
Democracy is established on the belief of capitalism i.e. separation of religion and state.
The democratic way of life emanates from a civilization established on benefit and neglects other values. Happiness in Islam is achieving the pleasure of Allah the Supreme. In democracy majority rules. In Islam, Sha'ria rules. Democracy sanctifies liberties.