The Marvels is anything but marvelous so far at the box office. Based on Friday earnings of $21.5 million, the Marvel Studios and Disney superhero tentpole is headed for a domestic opening of $47 million to $52 million to rank as the worst start in the history of the Marvel Cinematic Universe. The Marvels marks a new low for Kevin Feige‘s Marvel Studios, which for years was unrivaled in its success, and bolsters the theory that superhero fatigue is a real thing as fanboys grow weary of a glut of titles and are far less forgiving. Until now, rival DC...