Nah, the lack of understanding is being blind. That is YOUR case.
I have zero interest in Sancho, BVB and United.
But how many excuses can you come up with?
ALL THOSE GUYS LEFT when they wanted.
So again, can you give me an example of a single big time player that BVB blocked from leaving when a big team came and paid the price?
The only example was Lewa.
And please you have to realize that when a player leaves 1 year before the end of his contract (Hummels or when Lewa wanted), HE REJECTED EXTENSIONS.
If Haaland or Sancho WANT to leave AND a big team gives up the money, THEY WILL LEAVE.
They managed to keep Reus who Bayern (and a few others) really wanted.
They did not sell Hummels or Gündogan when they had multiple years on their deals.
Auba wanted to go a few times before he ultimately got sold.
They rather kept Lewandowski another year and let him walk for nothing than let him go for a decent fee to Bayern..
All those guys left when BVB ran out of leverage. Pulisic, Kagawa, Götze, Mkhitaryan, Lewandowski, Sahin, etc...
Dortmund did not want to sell any of those guys.
But given their financials and status they could not convince them to stay so they sold them because that was the less painful option to losing them and a ton of money (with the exception of Lewandowski which really hurt them) once they run down their contracts.
That is vastly different from the ridiculous assumption that they are happy to sell if someone offers them a good price....
Haaland and Sancho obviously will leave Dortmund rather sooner than later. No question about that.
But only once Dortmund are forced to let them go.
And in both cases that won't be in 2020 unless Sancho pulls a Dembele and even then I think Dortmund would be more likely to keep him not to mention that I don't think United will pay enough for Dortmund to give in now even if Sancho goes full ballistic...