As long as they make so much money in sales of their players it wouldn't be important for them whether they are champions or not. I assume the fans think the opposite but they must be also aware of Dortmund's policy already. Otherwise Dortmund can easily build a squad that can be much more competitive for the league title to win.
We should not forget that Dortmund was basically bankrupt in the early 2000's because they made so much debts with stupid transfers in the years before that. Then Jürgen Klopp became the coach of Dortmund and then they started to rise again and they won the Bundesliga two times with him and they even made it into the final of the Champions League.
In the last few years it became their business model to buy young talents and then sell them again for high amounts of money.
Of course those were really hard times for Dortmund. But it seems like they have learned their lesson from that as we don't see such unnecessary transfers. They are only focused on reasonable transfers in which they can make a big profit. Sometimes things don't go exactly as they imagine as well of course.
For example Haaland could have been sold for a much higher amount of money considering that he is a very special striker. At least the same thing didn't happen with Bellingham. They need to be more careful with release clause cases while they are signing such talented players.