It looks like they didn't do that last year and spent a lot of money on transfers, but they need to start making some profit on transfers to cover the difference without a doubt. I know that it will take some time and it's going to be a lot of years before they can get rid of it and the salary cap situation would be better for them, but it looks like we are talking about a situation that doesn't really hit that well for many people.
Barcelona will never ever make a profit from its sale. I remind you that how much money wasted for coutinho, dembele and griezmann. Barcelona was just able getting small amounts of money after selling those players back again.
Barcelona is always in bad financial condition.
This was one of the downfalls of Barcelona's management in the previous era as they seemed to have no love for money and instead made some senseless purchases with huge sales and losses in the end.
More than 400 million they spent on these 3 players if calculated in total but the performance and return can be said to be a failure and indeed as you say this is not profitable but seeing Dembele leaving of course the price is not too much of a loss when compared to Griezmann and Coutinho.
But this is a good lesson for Barcelona not to do the same thing and not let incompetent people behind their scenes.