The Chinese Revolution
After decades of warlordism, Japanese invasion, and civil war, Mao Zedong's communists defeated Chiang Kai-shek's nationalists, who fled to Taiwan — a division unresolved to this day. Mao then attempted to force China into modernity at speed. The Great Leap Forward collectivized farming and ordered peasants to smelt steel in backyard furnaces; the resulting famine from 1959 to 1961 killed somewhere between 15 and 45 million people, among the deadliest in recorded history. The Cultural Revolution that followed turned the young against teachers, officials, and their own parents, and shut the universities for years. A quarter of humanity was governed by a state attempting to redesign society from first principles, and the cost was borne mostly by the people it claimed to serve.
Hardship plus a sudden opening (weak state, lost war, fiscal collapse) lets those who bear it overthrow the order — usually installing a new elite.