Perhaps an interesting extract from that 3rd article in your list....
"The aforementioned are all ways of effectively increasing revenue, but that is without mentioning player sales.
Like any club that gets taken over and improves its standing within the European game, there will always be players moved on who don’t quite fit in with the team’s plans any longer. Recouping a sizeable amount of the original fee paid for the player—or in other cases, turning a profit—is another part of PSG’s strategy. "
So, by selling players some of our players at a profit we are simply emulating the PSG model of revenue generation.....