Life is constantly moving forward, which means you will never stay in the same place for too long. Sometimes you're up, sometimes you're down. For Riggan, he was at the top of his game when he was playing Birdman. After he moved on from the role, he lost his popularity—and his ego took a major hit. But rather than find happiness and comfort in a quieter, more fulfilling life, he wanted to get those glory days of success back.