Barcelona aren't going to win La Liga next season. Might as well sell Frenkie and Ansu to a team that will. I'm sure you'll understand that type of argument.
You may not think we'll win the league next season, but when a club hierarchy fails to such a degree and comes under pressure, it's probably not a good idea to do things that'll anger your fans even more. Fans don't care about maximizing a transfer fee. They make plenty of money. They're set to lose a smaller share of money than most every big club around the world.
Fans can accept Sancho will probably go this summer. He was never likely to be a player that could be enticed to stay. We were lucky to keep him last summer. Due to their poor decisions in the managerial department since Tuchel we have failed to win the league when we should've done so at least once. They owe it to their fans to put the best team on the field they can next season with a better manager. When your best player wants to stay and hasn't said he's not willing to extend, you don't sell him abruptly to maximize a fee. If we win the league next season with a better coach and he gets a big extension, maybe Haaland will stay. Reus stayed when he had interest from much bigger teams.
Even if he doesn't stay eventually, there will be huge backlash if Haaland is sold without asking for a move just to get a few extra dollars that might not even be offered this summer. Fans don't only exist and get mad at the five biggest clubs in the world. You saw what happened with Marseille? If your management runs a club ineptly and angers fans, there's going to be backlash. Dortmund hierarchy aren't on the best terms with their fans right now. Selling Haaland to maximize a fee is probably the worst thing they could do this summer to make it worse.