alt Hacker NewsThe answer to your question "are these last 80 years really peaceful?" is yes, in context. Look at the horror of the world wars, or the preceding ~1000 years of barbarity and wide-scale religious wars. The US does not always use its power wisely, but the alternative is to cede that power to someone else: nature abhors a power vacuum.
Modern anti-vaccine nuts have spent so long living without measles that they've forgotten the good that vaccines do and take their good health for granted. Anti-US-power nuts have lived in a world largely without large-scale conflicts, held in place by our NATO allies and the credible threat of force, and you've forgotten what a world without that stabilizing effect looks like. Spoiler: it looks like the 30 year war but with nukes.
I'm not "Anti-US-power", I'm anti-genocide, anti-terrorism, anti-war-crime, anti-torture, anti-invading-sovereign-nations, and pro-democracy. It's not my fault that the US has systemically made deliberate attacks against civilians, war crimes, rampant human rights abuses, invasions of sovereign nations, and overthrowing of democratically elected leaders the basis for US foreign policy and military doctrine for the last century or so.
When you ask me to look at the horror of the world wars, does that include the horror of the only country to ever use atomic weapons in conflict deliberately dropping them on cities they knew were full of civilians? If that's what the American version of "peace" looks like, I'm not interested in the American version of "peace". The Soviet Union never deliberately nuked New York. China never deliberately nuked Taipei. North Korea never deliberately nuked Seoul. Iran never deliberately nuked Jerusalem.
You propose a hypothetical future where you guess that a world without US "stability" involves nuclear weapons, while ignoring the fact that the world with US "stability" already involved them. History speaks louder than hypothesis.