It's undeniable that Ademola Lookman is Atalanta's second main striker, who not only provides a large contribution to Atalanta but is also a strong leader for the entire team. Atalanta previously lost Mateo Retegui, this Center-Forward chose to move to Al-Qadsiah, a decision that was very shocking at the time because with his position as one of the top scorers, it was hoped that he would still be in Europe, but it turned out to be to Al-Qadsiah.
This year Atalanta probably calculated that they would go backwards, that is, that they would have a worse season than last year but still earn money, so they continue to do this.
I think it made sense in the past, but now the team seems quite strong to me.
I have this impression too, I think they try to get the maximum profit from each disposal and collect as much as possible.
From what I've seen so far the money from the sale of Retegui has not been invested, and if they ever sell Lookman I think they will do the same.