He didn't want to be here because Pep was making him do the hard work he expects of everyone.
The undervalued stuff is nonsense, @tolmie's hairdoo can confirm, but he was given triple his Schalke wages when he signed (60k), and then offered treble that 2 years into a 5 year contract. He turned it down.
Leroy can be summed up by the tattoo on his back. Not only is it a tattoo of himself, it's a tattoo of him scoring in a game we lost terribly. Most players would never want to be reminded of that game, but for Leroy him scoring a big CL goal was more important than the result. And to doubly enforce that message, he scrubbed the City badge off it a few months later. He's all about the individual glory.
And then we go into 18/19 when Pep is beside himself trying to get him to make the runs the team needs him to, or to track back with the ball, until eventually when the going gets tough, he barely starts a game in the run in because Pep doesn't trust him.
He's a phenomenally talented player, but he and Pep never saw eye to eye, you could see that in the Amazon documentary during a season when everything went well and everyone should have been getting along. The same attitude is why he got dumped out of the Germany team for the world cup and none of his teammates stood up for him.
I think there's every chance that he goes on to do very well for Bayern, which for €350,000 a week + whatever 8 figure signing bonus he gets will be the bare minimum, but I guarantee he has more fallings out with managers. And he'll probably change his agents another few times as well if the last 12 months are any indicator.
I hope he hasn't lost anything from his injury, and I expect like Yaya, Ibrahimovic, Eto'o, Mandzukic he will have a great career after not seeing eye to eye with Pep, but as far as Manchester City are concerned, he was never going to reach his potential here because he wouldn't do what Pep wanted. Now lets spend the money on someone who will.
Lastly I think it's disingenuous to say we opened the door for him. He was one of Germany's most highly rated prospects for years before we bought him, he was making international headlines scoring a screamer in the Champions League when he was 18. He was very much on the map and we picked him up at the right time.