> The last time the world had multi-polarity, we had far more wars. Including the worst wars the world has ever seen.

Citations? Simply saying that World War 1 happened during a time of multi-polarity is just begging the question. Multi-polarity of varying degrees has always been the case throughout human history, and often times single-polarity is achieved only through extreme violence.

American Hegemony or Pax Americana (post WWII until present) is the most peaceful period of human history, despite the myriad atrocities which have occurred during that period, from myriad different parties, including the USA itself

A big reason for that, as far as I can tell, is that if one side has the USA on its side, they're basically unattackable for many places since the USA is so over powered militarily and can project force anywhere

It stands to reason as the USA recedes from the world's stage it will get more violent as more nations stand at parity with their adversaries again. And we're certainly seeing wars cropping up lately as the US continues to undermine its traditional allies, bully adversaries, declare trade wars, and withdraw from agreements.