I also believe that Dortmund has that business model, for me it is one of the clubs that have the most to be able to get their hands on the best players, or we can deny that Lewa came out of there, also Haaland, so I don't know If that is as good or better than winning a Bundesliga or even winning a UCL, what I have in my mind is that if we put these things in context, does it make more money to do it like this or by winning? because by winning I know that apart from receiving a very good reputation they can have good rewards to be able to give them to their players and to the club, in addition I don't see a bad thing that they can train them and leave them there for themselves.
I know dude has a potential and he looks like a great future star but paying insane amount of money for him would be a mistake by Chelsea. Plus if Dortmund could get him to sign another contract, he could play there on every single game until he is sold to another club for a huge sum, and he could get to a better place.
Now, he would be going to Chelsea, not a great team now, and be benched there and would probably not be seen by the world much. Staying at Dortmund at this age would be a better idea, so he could get some time and show his skills to the world. But at the end of the day it's something only he could make a decision out of.
The problem is his staying at Dortmund is also not gonna be the best decision in my opinion, because Dortmund is also not able to perform well currently. I also feel like there is no point in performing well in a team that is not going to be successful anyway. I believe that it is not good to win trophies with a team, for which a player did not play at all and had the same time, It is also not very good for a player to perform decently in a team that is not going to be successful eventually.
I am not going to say that his going to Chelsea, is going to be a big problem for him. Because for a player like him, he is going to prove himself whenever he gets the chance.