The fact that Democracy has had a really good run for the past 100 years is nowhere near a guarantee that Authoritarianism won't rise again for the next 100.

You can easily argue that the rise of Democracy in the 20th century is simply because the United States won world war 2 and the cold war, and all other countries adopted Democracy just to emulate the US.

If Germany had discovered the atomic bomb before the US (which arguably could have happened if history were just slightly, randomly different), the world could be radically different. We could all be arguing right now that Democracy is just too weak to survive.

I'm saying that before World War 2 you wouldn't generally consider Democracy to be the default paradigm for how nations were governed.

There were many other democracies, and pro-democracy movements that preceded WW2 and had nothing to do with the US.