Josep Maria Minguella, the coach and agent who brought Diego Maradona, Romario and Lionel Messi to Barcelona, believes that Catalans' members-owned club model may cease to exist in some years.
The Blaugrana decided to sell part of their TV rights for a few years in exchange for capital in their bid to balance their books and sign new players.
"[Barcelona president Joan] Laporta understands that the excitement returns by strengthening the team and signing big names, but in football you have to see the results," Miguella told Radio MARCA.
"You have to think positively and from there, the excitement returns. On the other hand, assets have been sold that could mortgage the club in the coming years and could lead to an unsustainable situation for the next president.
"Barcelona could be doomed in a few years to have a model like that of Bayern Munich and cease to belong to their members.
"The sale of TV rights, the Espai Barca and the renovation of the stadium represent an investment that cannot be returned at a football club.
"The solution in a company would be to increase capital, but as there are no such capitalist partners at Barcelona, a solution would be for a capitalist partner to come in with part of the money. I would be very unhappy about that."
Minguella went on to break down the reasons he is against Lewandowski's signing. The Poland international departed Bayern Munich to join Barcelona last month.
"Barcelona always has to aspire to everything, even if in some years they have signed badly," added Minguella.
"The only way to amortise [Robert] Lewandowski is to sign him for four years, which seems to me as a big risk.
"I am in love with the Lewandowski of 20 years ago. He is a great player but he has only played in Germany where the football is very different.
"He is a great striker but here he will have more problems because there is less space. He is a star signing.
"Barcelona's main problem is that they have seven strikers and there will always be four on the bench and all the players want to play and this situation can create problems for Xavi [Hernandez].
"I think Barcelona have too many players and it's difficult to manage. The best teams in the history of football are the ones where the fans know the starting XI by heart. And this happened when Xavi was a player."