The Decline of Anarchism in the 20th Century

In the 20th century, anarchism ceased as a mass revolutionary movement (except perhaps in Spain in the 1930s). Why? I give three reasons here: the internal momentum of the state, reaching its culmination as a war and genocide machine; the internal direction of the left, particularly around Bolshevism, toward extreme statism (from welfare state liberalism to socialist state control of the economy to state communism); and the terrible strategic and ethical mistake that anarchists made around 1900 to engage in assassinations, bombings, and acts of terror.