In the last 10 years or so, Mourinho hasn't been that great, last "achievement" we can say was Roma getting conference league, but looking at their opponents, 90%+ of them were worse than Roma, the only team they beat was at the final game.
So the reality is that, Mourinho has bene on a decline for a while, from his peak at Real Madrid, to be a manager at Turkish league is proof that he is getting worse. If he was that great, he would have been managing a better team, why would he be here. He would be managing Manchester United for example, they needed a manager, if they believed Mourinho was good, they would have gotten him. Obvious that he is going to go to Saudi league after this, he is just chasing that famous 10+ million worth sacking money.
In Türkiye, the most career managers have worked continuously. Many Real Madrid managers have come here before, during their prime. What you say is not valid. Managers go where they can earn the most money, naturally, like any other personnel. If they can earn more here, why wouldn't they come here? Aragones, Del Bosque, Löw, Lucescu, Schuster, Feldkamp, Rijkaard, Milne, Hiddink, Toschack, Tigana and many more, what a big career managers. They all came and managed teams here. Mourinho is not superior to them, of course he will come when it comes to money. Besides, Mourinho has only been successful for 6-7 seasons in his 25 years of manager career. In the rest, he always failed and was sent away with compensation. It's known that he is one of the names who loves money the most. I'm sure he came running the moment Ali Koç made the offer. And that he wouldn't want to leave. He will get that compensation again and that's how he will be fired. Or he will continue to cry next season.