This man owes everything, good and bad, to his stubbornness. He was stubborn enough to spend two billion years managing Serie Z level clubs, and finally reached the top level. Most people in his shoes would quit such a career way before he got to the top division. But the very same stubbornness didn't allow him to succeed at the top. And since it's the core of his character it was ridiculous to expect even the slightest flexibility from him.
Anyway, he's a great example of how far you can get if you just don't give up on your idea no matter what.
Also, I believe that his constant excuses are actually what helped him to keep going down this road regardless what happened. This is just a coping mechanism, which when combined with stubbornness gave him what he got.
Because of all of this Sarri had zero chances to succeed with Juventus and that's why he was such a misfit here. And yet his personal story is quite fascinating. Many people can learn from it. I wish he could learn something from others as well.