It’s systemic risk Mike. I think your timeframe is incredibly misleading - liberal democracy has been established since the 18th century. I don’t disagree that we’ve had a relatively peaceful period of history, especially in the Western world, since WWII. But I think it’s undeniable that the structure of the system is cycling back towards chaos and destruction, as you seemed to agree with.
Here’s a chart of the bank failures since 2008. Looks oddly similar to your battle deaths chart. From a structural, foundational perspective, the current monetary and governmental system is designed in a way which creates great death, destruction, and poverty when there shouldn’t be any. I would rather have consistently more localized and individual crimes with slow increases in prosperity over time than massive top down controls causing booms and busts, both in prosperity and in safety. 

