Real Madrid is evidently in pursuit of such high profile players as Kylian Mbappe and Sadio Mane. Both those players are young and good...and valuable. Any world-class club would like to build around them. So why would PSG and Liverpool let them go?
Deloitte's 2019 Football Money League shows that Real has annual revenues of €750M; while PSG is at €540M and Liverpool is at €510M. Real is richer, but not by much. Let us say that Mbappe transfers for €300 and Sane for €100. If we amortized the transfer fees over 2 years; then Real's annual income is down to €550M, a year; no real advantage over PSG or Liverpool. So, even if Real doesn't pay to transfer in another big name for 2 more years, the high cost of the transfer fee means they shouldn't be able to offer a more lucrative contract to the players in question than other world-class teams with high revenues.
In general, I don't understand how any of the top tier teams are able to afford to transfer player from the other top tier teams. In some cases, like Ronaldo going to Juventus, it seems that it was the player's idea to make the move. But absent player unhappiness, if Sane is happy in Liverpool, then why can't Liverpool pay enough to keep him?
How does Real Madrid, in particular, have the financial muscle to buy whoever they want, even from other teams with top-10 revenues?