This is something that's been going on over the years and they're not bothered about losing their most valuable player because they've got good scouting network across Europe that helps them recruit new youngsters from teams all over the world and to be honest I don't think any team would had been able to challenge a squad that had Lewandowski, Haaland, Sancho, Bellingham and several other top talents across Europe.
I've always considered them a business minded Club because if they really cared about winning a trophy they would had utilitized the players they had instead of developing them and selling them out to others top clubs while it reduces their performance, the sale of Jude Bellingham is really affecting them this season because was their star player but they've cashed in on him and made Realmadrid more stronger.
Dortmund us never a club to talk about, they're another version of Tottenham Hotspur in England. No ambition like they're ready to get into 3 finals and lose them all.
Dortmund have groomed better players like you said but what's the point in getting those players to play their sweat out and at the end of the day is just nothing to show for it.
These days clubs spend to get results (trophies) and not fall back to the money, fine is good to make money but what use is the money when there's no trophy to show for it?
The only man I feel for is Marco Reus, that guy has been on the neck of Bayern Munich since his arrival to the club Dortmund (10yrwband still counting) but all his efforts are for nothing, playing with some of the best players just to get his name to that trophy but no way, too bad to be in a club that has no winning mentality. I believe they (Dortmund) can't get back to that excellent form again.