Getting a title is definitely something that makes players more valuable, but also not getting it will make them go down a lot more. Meaning, if any player at Leverkusen is overvalued right now, that means they could be even more overvalued next season if they win it again, however they would crash harder if they end up failing.
Look at how valuable Osimhen was last summer, you could have found a team willing to spend 100 million on him easily, look at him now this season, still the same? Of course not. Meaning, if Leverkusen wants to make a profit from their players as quickly as possible, then they should sell them right now, or they are facing a possibility of losing their value next season if they end up failing to win the title. Or they can wager on their talent, and if they win again, it could be even more valuable as well.
I don't think Leverkusen will make money by selling their players right now. If this is what Leverkusen wanted to do, then Xabi Alonso would have been the coach of a new team this season as well. He did not stay as Leverkusen's coach. I think Leverkusen will definitely try to win the title next season. Leverkusen will want to dominate the Bundesliga. Selling the players will transform Leverkusen back into a mediocre team. I think Leverkusen management will not make this mistake.
If Leverkusen is like Napoli next season, Leverkusen will surely suffer a big loss. You are right. But what if Leverkusen can win the title again? Indeed we should think of two options.