The Russo brothers don't believe in the superhero fatigue theory. Before the Marvel Cinematic Universe started struggling to reap the same impressive financials at the box office, with underachievers like The Marvels, the Russos cranked out hit after hit for the MCU. And the siblings helmed the two biggest moneymakers of the entire franchise Avengers: Infinity War ($2.1 billion) and Avengers: Endgame ($2.8 billion).