Once a competent authoritarian leader takes root, it becomes very hard to remove him: the necessary mechanisms, formal or informal, tend to be sabotaged - not at once, but more and more over the years. It also helps when some of opposition have their lives broken, when uncertainty about one’s own life is high, the value of human life low, when loyalty is placed above both competence and the law, and the law above competence, when the reputation of any possible contenders is questionable or made questionable, when people are used to the thought of futility of resistance (with fresh examples produced all the time) and being alone before the oppression, when somewhat educated people are made to think their views are in minority (independently of whether it’s the case) and some of less educated people have some of their misery alleviated (and are occasionally given some power they did not deserve) in return for voicing the pro-government position (even if a good measure of said misery is a consequence of the government’s actions).