I'm thinking from his perspective. He's the best player at the club, but the club isn't quite at the level needed for him to be recognised as a world star.
It's a similar situation to the likes of Modric, Bale, and Ronaldo, who were never regarded as big stars until they landed at RM.
I've said it for years; as much as we don't like to hear it, we'll never be as big as RM as a club. It's the club every player dreams of playing for. That's why Haaland will almost certainly end up there in the future.
Bernardo Silva is more than good enough to play for RM in my opinion. He'd achieve more there as an individual than he would at City. And he'd be doing it in warm weather, closer to his homeland.
That's why he's too good for City.