I also wonder if this is a prudent assumption. Existential threat is really hard to measure. If we want to know the average lifespan of a modern republic that h

I also wonder if this is a prudent assumption. Existential threat is really hard to measure. If we want to know the average lifespan of a modern republic that has existed for about 250 years already, we don't have many data points to compare to. Here are ones that may count: - San Marino has been a republic for over 1000 years - The Netherlands was a republic from 1581 until 1806 - Switzerland has been a republic since 1648 - Paraguay, Chile, Argentina, and a dozen other Latin American countries have been republics continuously for over 150 years. Not without their share of upheaval, but even in the case of Venezuela I don't know that you can argue that the country stopped existing in sudden crisis. And that's all I can find, for "modern" republics >= 150 years old at present or at cessation. The next closest is France, which is also still a republic. We don't have too much data but I would listen to an argument that modern republics seem to be unusually long-lived compared to more traditional government types. With no better information available, you can choose either to trust the examples we have, or to adopt the doomsday prepper mentality. When trust is cheaper, it's not any surprise to me that people trust the government to continue existing.