While we've lost money on a couple of those players in terms of fees (although losing just €2 million on Capoue who only made 36 appearances for us isn't too bad at all in my opinion), its worth remembering that we turned a profit on the Bale transfer window and will probably turn a profit or at least come very near to breaking even in this one too. While we're losing some money on individual players you do, I think, have to view the transfer business in terms of all the players moving around, not just on individual deals. It's be great to turn a profit on every player but that isn't always going to happen, especially when you take the apparently scattergun approach to transfers we took when spending the Bale money, and that Liverpool took spending the Suarez money.
Your point about wages is important and of course clubs spend huge amounts of money on paying players. That said, Spurs don't have many if any truly massive earners (in footballing terms at any rate), and its fair to say that most of our top players could definitely earn more elsewhere. Rightly or wrongly, I think many fans think of transfer fees in one bracket of comparison (thats definitely how I simplify it all the time), and assume that wages are financed differently. This is probably a little fairer, if still inaccurate assumption at Spurs because nobody is earning stupid money like Rooney, for example, although the way that all clubs finance transfer fees and wages and all other costs is surely far more complex than simply keeping fees in their own bracket and pulling in wage money from a different part of the budget.