Angel di Maria's unrealistic wage demands led to his departure, Real Madrid revealed at the announcement of their 2013-14 financial results.
The Spanish giants confirmed on Friday that their revenue for last season " in which they won the UEFA Champions League and the Copa del Rey " was 603.9million, an increase of 10.9 per cent on the previous financial year.
"For the 10th consecutive year, we will be the club with the biggest revenue in the world," Real president Florentino Perez declared.
Perez has been questioned over the sale of Di Maria - who moved to Manchester United for a British record transfer fee of £59.7m last week - despite the close-season acquisitions of James Rodriguez and Toni Kroos.
But Perez announced that the sale was necessary because Di Maria wanted far too much money to stay at Real.
"He had economic demands that we could not satisfy," Perez added.
"We made our best offer at the highest level we could and he did not accept it.
"With the exception of Cristiano Ronaldo, who we all know is the best player in the world, no other player has that level of income.
"If we had accepted Di Maria's economic demands there would have been unequal treatment and it could put the economic stability of the club at risk.
"When faced with his rejection of our offer we began to think about other players and brought in Rodriguez."
Real also revealed that their net profit after tax stood at 38.5m, a 4.4 per cent rise, while their net debts totalled 71.5m, a 21 per cent decrease.