No matter how business minded the Borussia Dortmund management wants to be, they should know that Borussia Dortmund should've been one of the strongest clubs in not just in Germany but in Europe at large.
I think the club should stop the policy of always selling their best players to another club but rather they should build a strong team that'll be major contenders for German and European competition in coming years from now. We must break the deadlock
I think it's become normal for Dortmund to buy youngsters, train them to be potential world class players and sell them to a bigger club for a huge fee when they're performing well and that policy have been going on for years and they've lost top class players like Lewandowski, Haaland, Sancho, Bellingham, Aubameyang, Dembele and several other players that are good as well.
If not that they sold all this player to bigger clubs across Europe Bayern Munich wouldn't had been able to challenge them easily maybe the would've ended the supremacy of Bayern long ago, especially when Halaand was involved in the team, I think this summer there might be another rising star that could leave Dortmund, (Karim Adeyemi) his performance has attracted alot of big clubs and would come after him by summer and I'm sure Dortmund would be very happy to cash in on him for the right price.
Dortmund's goal is to buy more and more young players and earn money from selling these players and that's their first priority otherwise they could keep the superstar palyer they had before.
Also, I think Dortmund is a great player supplier for Bayern Munich and there are many players from Dortmund who left this team for Bayern Munich because Dortmund could earn a good amount of money.