Van der Vaart struggled for regular minutes, but admits his profile was raised by being with Real.
"It was hard to leave Madrid. Madrid is a fantastic place, a club amongst the strongest in the world," Van der Vaart told La Gazzetta dello Sport.
"There were so many players - me, Wesley [Sneijder], [Arjen] Robben - we hadn't got the space we thought we had.
"Real Madrid gave me money, a chance to be famous, playing big matches. I will always be grateful to them."