They have a story up on ESPN about their strategy for making a return on Bale's fee and it makes more of a marketing case than a football one. They are talking about shifting their focus from East Asia /Latin America by selling Kaka to the "Anglo-Saxon" market by acquiring Bale. Any other club that bought a player for some 60million euros or whatever they spent and let him go on a free would have been ridiculed but Real under Perez uses strategies most clubs wouldn't think of tbf.
This was beyond obvious to me. They get a good English-speaking player to market and they don't ever have to worry about him playing in summer tournaments, so he should, in theory, always be fresh when they need him.