Let me elaborate: I think we see this type of historical person everywhere in history. A figure who early on and maybe even quite a bit into their life seems unstoppable but then, gets defeated and never recovers. How bad this defeat is varies, Saladin, for example can mostly be said to have lost his final war and had to cede some parts of the Levant to the Crusaders, but got to keep many of his conquests. At the other end of the spectrum is Napoleon, who ended up with much of France being occupied and him being deported to an island in the middle of the ocean. But the formula is still the same. Some examples are:

Saladin who I mentioned, who finally retook Jerusalem after 100 years, but then got defeated by Crusaders. (Even though his reign was a success since he kept much of his conquests)

Napoleon, who I also mentioned, defeated the coalitions of Europe again and again, but then botched his invasion of Russia and then was defeated.

Charles XII of Sweden who won early fantastic victories against Denmark Poland and Russia, but then after an attritional invasion of Russia was defeated at Poltawa.

And of course Hannibal, who upon invading Italy steamrolled through Roman legions in three battles, the third of them being one of the most tactically decisive victories of all time. But he never marched in Rome, instead just waiting in Italy until he was called back to north africa where he lost at the battle of Zama, after which Carthage suffered a brutal peace treaty.

So it seems to me that this type of figure pops up all the time in history, so I ask you, why does this happen so often?