Joseph Tainter has a theory (The Collapse of Complex Societies) that civilizations gradually increase in complexity, then collapse when the benefits of addition

Joseph Tainter has a theory (The Collapse of Complex Societies) that civilizations gradually increase in complexity, then collapse when the benefits of additional complexity become negative. Collapse can be, and occasionally has been, prevented through making simplifications, but there's usually resistance to that. There's only one civilization left. If it collapses, collapse will be global.