What has me being a Leverkusen fan to do with my opinion on the matter? It's not like I want you to act like Leverkusen on the transfer market. I',m suggesting you should act more rational. I mean, even if Haaland leaves after 2.5 years for a small fee, what's the matter? You guys yourself said that money isn't important to you. Meanwhile, the guy would probably have netted 40+ goals for you throughout those 2.5 seasons. It would've been the rational decision to sign him. The irrational one is to reject him because he doesn't want to commit himself long-term to a club who was once great and is in a uncertain change process right now. You could develop like Liverpool did or you could the same route as AC Milan. And you want those young players to commit themselves long-term to you? I mean, why would they do that? What do you think would the motivation behind that behaviour be? That they've been life long United fans? Good luck. The world doesn't revolve around you, there are much more attractive destinations currently than United. You need to arrange yourself with that situation. You're not in the same bargaining position as 5-6 years ago.
I think your club needs more pragmatism and less pride. More controversial, possibly unpopular but ultimately right decisions instead of the usual "we've always did it this way" mantra. I mean, imagine a world in which you'd have signed Haaland with the clause. There would've been a chance that you develop well and he wants to stay beyond those 2.5 years. But even if he leaves, what's the problem? Yes, it would be bitter for a short while but you'd have gotten 2.5 good years out of him, he would've improved your reputation as a club with a perspective for young players and you probably would've had enough time to find a replacement for him.
All the issues you're having with signing Haaland are ultimately of symbolic nature. And symbolism doesn't win you anything.