It is true that when a club sets such a high price for a player, it actually says that this player is not for sale, but if a buyer is found for such a high price and they will be able to make an appropriate replacement, for this money. On the other hand, I constantly see how prices for players are constantly rising, if earlier it was a wonder to hear the amount of 100 million, now it has become the norm for almost any top club.
Usually clubs who want to retain their key players set high prices so that other clubs cannot afford to recruit these players because they are too expensive. But for clubs that are rich and capable, they usually don't care even if they have to buy at a high price. Even if their potential is guaranteed, they can play well in their new club and can make a promising contribution, but if they don't change and tend to be mediocre, it's just a waste for the club recruiting him and causing losses to the club that bought him at a high price even though the expectation of every club buying a player is that it can improve the club's overall performance and provide maximum performance.
Alexander Isak is an important player that Newcastle has so it is natural that Newcastle will set a fairly high price for this player, in other words, Newcastle still wants Alexander Isak to stay at Newcastle longer. He is also still young so his potential is still quite good. But the question is which club can afford to buy the player with the agreed price given by Newcastle. I think club like Arsenal and Tottenham of course think long and hard about recruiting him even though they can afford to buy the striker even both clubs are rumored to be interested in the striker.