Your final sentence is the point. We didn’t have 1000s of nukes worldwide back then. If no one will dare to stop Russia attacking Ukraine with any meaningful amount of force under threat of nuclear war, why would anyone attack USA?

What about North Korea? Everyone knows what’s going on there isn’t right, but I don’t see the world banding together to overthrow their government and change things.

I think the 100 men vs bear meme is pretty relevant here as well. It’s one thing to say IF every country bands together they can take on USA, it’s another thing entirely to say you could get the world to all agree to that at once. And whoever makes the first move would likely be decimated.

And you’re right, if USA is backed entirely into a corner, Trump is crazy enough to press the nuke button. All it takes is him getting a few high up fanatics to go along with it. So the bear is also wearing a dead man’s switch.