5. He's Had Enough Of Marvel
Joss Whedon has made it very clear in recent interviews that he doesn't intend to return for the two-part Avengers: Infinity War. He made similar comments after The Avengers was released and received a huge pay increase to come back and helm the sequel, but he seems pretty adamant that his time in the Marvel Cinematic Universe is now nearing its end. What the director won't want fans to know is why he's really leaving. Sure, he puts it down to wanting to create something original, but that feels more like a convenient PR friendly answer. It could be that like a lot of other directors, once or twice working under Marvel's watchful eye is more than enough and he's ready to leave them and reclaim his freedom.