I'm relatively new to the game, so I haven't witnessed a big part of world history here. But from what little I've experienced, even countries that seem INVINCIBLE™ eventually collapse spectacularly.
We've witnessed the fall of the Netherlands and the Philippines, with Turkey soon to follow. What even causes these collapses in the first place? Is it them getting backstabbed by their allies? Were they never even powerful in the first place, and instead were merely a proxy of actual great powers? Administrative mismanagement? Just collapsing because of time itself? I don't know.
But I know y'all know, so I'd love to hear your thoughts. I personally think it's just the countries not having much of themselves, overextending with the hell of allies, but then collapsing once organized revolutions annihilate them.