Depends on how you look at how a football club should be run.
Firstly, would we all agree that football clubs should lose millions of pounds each year? I'd imagine, we'd all say no to that, regardless of who that debt is owed to, there's not much difference between Man City and Sheff Utd in that respect. It's not good practice, it's asking for trouble and leaves us vulnerable even if we only owe money to our owner. Therefore, one way to balance books is to make profits on player transfers.
But, the problem is is that we are selling players, making profit on these by the millions, and still losing millions each year and with all that in mind, we are getting worse on the pitch, from the Premier League to League 1 in a few years, with all the losses that come with it. In short, the people running the club no matter how admirable we think they are for dipping into their own pocket ("just sign this paper transferring the ground over to the holding company please"), they are running it un-businesslike. If we were run well, then we wouldn't be needing to sell our best players. It's because of those at the top that we are in trouble; they haven't saved us, they've put us there (with good intentions I admit).
Blackman hasn't gone yet that I know, and the longer it drags on the more he's likely to stay or we get a better price, but the bigger question is how we want SUFC to be run and whether those running it are able to do so.