Tangled cost over $300 million to make.
Granted, it was worth the investment because Rapunzel is now one of the company's #1 merchandise monsters, raking in billions each year. And a spin-off + Broadway adaptation are in the works.
But it did not make a profit at the Box Office.
And for Disney, this is what it's all about: merchandise and longevity. Monsters, Inc has been a top moneymaker for years, MU was simply a little boost for merchandise sales. Just like Cars 2 and Planes were boosts. The millions they spend in production are recouped through merchandise sales. It's easy to sit here and judge a movie's performance solely on Box Office when we know nothing about how it performed in other aspects. Hell, we don't even know what Disney's targets are.