I’m going to just say that Riggan is Steadfast. To me there’s a couple reasons, for the entire film he tries to suppress Birdman because Birdman threatens his credibility as an artist. He’s meditating in the beginning to shut out Birdman’s voice (according to an earlier draft of the script), he destroys the poster, and perhaps in a bit of an homage to Fight Club he attempts to shoot himself to end the alter ego for good.
Second, he chooses to pawn his problems off on others. His preference is to avoid consequences. He tells his lawyer to make the law suit go away, he tells his producer to fire Mike after he embarrasses Riggan at the first run through, when his daughter questions his relevancy he ignores her until she leaves the room, he wants to quit when he is afraid he’s losing his mind and control of the play, and finally, so as to not face the embarrassment of failing on Broadway he tries to kill himself and accidentally misses.