The corruption amongst the wealthy and the powerful, as well as overreach of power from the central state causes instability in the empire, and with revolts, crisis and invasions abound, the empire collapses, and a new one arises like a phoenix out of ashes, along with a new era of prosperity where government officials work to the benefit of the people.
Dynasties in China rarely last more than 300 years before the corruption and the reach of the state expands too much and collapse the dynasty with it. The current global hegemon is the United States of America...How long has it been since the last rebellion in the Americas, against the last global hegemon before them, the British Empire?
239 years.
I am optimistic my future grandchildren will live in more optimistic times than my future children will.