Think is he's not better than bravo and winning matters first
Marc has never been the sole reason for losses, ever. He made some stupid mistakes in the past but was just as important in the CL as Bravo was in the league. Add to that his age, his potential and his playing style and you'll see why it'd be stupid to sell him.
Bravo might be marginally better than Stegen right now but the latter has the potential to become the best keeper in the world. That, to me, is unquestionable.
Young & great GKs are incredibly hard to find + not everyone will be suitable for our style of play. We signed THE keeper who has everything a potential world-class GK needs to have. Why sell him? Because Bravo is better RIGHT NOW?
If we sell him now, we'll find ourselves desperate for a good goalkeeper in the near future. It's inevitable. And I'm pretty sure that we'll end up with a much worse player than Marc.
Not directing this at you but people should stop pretending that Bravo is miles ahead of Marc. He isn't. I agree with those who say that he's better but to me it's not that much of a difference to justify seeling the younger keeper with much more potential.