Don't worry. It's dortmund's business. This team will be always doing it forever. Winning a trophy was just bonus but generating more and more money from selling developed players are very smart.
Even if they don't have supremacy in the bundesliga, they make simple earnings every season, which is why their predicted budget for a year takes longer to execute. They have no financial difficulties, they don't take out too much, and they also don't give in too much. Dortmund's economic model has evolved over time, with the goal of acquiring promising young players and profiting from them when other great clubs come calling. They're quite good at turning down offers from elite clubs, making three times the money they used in the market; this picture alone justifies everything. What I did not understand is how they get exact replacement of what they have already stood and if not better replacement of the player every season. Some times they will even get more than one star players in the same season and they will even sell both of them and still perform good and will still have another replacement next season.
Just after Haaland left, we thought it was over, from no where they have developed Jude Bellingham. I envy their strategy of making money.