His box office failures consist of two movies: The Guilt Trip (which made back its upfront budget of 40 million) and the Funny People which did the same. Guilt Trip came out 2 years ago, Funny People came out 5 years ago.
That literally means that out of his 10 movies, he has 2 which made as much as they cost but weren't box office bombs. That means that 80% of his movies have made a sizeable profit. Your assertion simply aren't true by any means. He may not be making thoughtful artsy movies, but he's returning studio investments in spades especially with his latest movies.