No matter what Dortmund must be still in a very good position financially. After Bellingham's sale they have made a big amount of money. This is their priority in the end so I don't think they are still thinking about how they can lose their title chance like that. Yeah it was really unbelievable but they are still able to reach their main goals according to their vision.
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.
Yes indeed, even though Dortmund continue to sell their best players but the fact is, Dortmund will still be fine and there is nothing to worry about for Dortmund. But indeed, if Dortmund really has the ambition to be better and stronger to win titles and trophies then of course, Dortmund must change this way or tradition. Therefore, Bayern Munich can consistently win the Bundesliga title, because its rival teams do not have big ambitions to win the Bundesliga title from season to season.
Actually, if Borussia dortmund wants to get the bundesliga cup, it will definitely be very easy, but borussia dortmund always sells their best players for business reasons for finances.
But lots of Borussia Dortmund fans want to occasionally make new history again without having to sell their best players.
Even if Dortmund cannot fully compete with Bayern Munich, being in second place is very safe.