It's hard to imagine now in a world where the characters have appeared in the highest grossing movie of all time, that there were doubts about the Guardians of the Galaxy beforehand. Even though Marvel Studios seemed invincible at that time the project was announced (officially revealed at San Diego Comic-Con in 2012), there were questions about if a film starring a talking raccoon and tree in space could perform at the level Marvel had established. Apparently even director James Gunn had those doubts.
When asked by a fan on Twitter how confident he was while pitching the movie that it would be a success, Gunn had a surprising but honest answer, he didn't know.
"I was confident I could make a good movie & that I was uniquely suited for the project," Gunn wrote. "I wasn't sure it was going to be a success, but my gut told me it had the kind of color, fun, emotion, and characters people were hungering for in their tentpole movies."
I was confident I could make a good movie & that I was uniquely suited for the project. I wasn’t sure it was going to be a success, but my gut told me it had the kind of color, fun, emotion, and characters people were hungering for in their tentpole movies. https://t.co/2pR5ectTLw— James Gunn (@JamesGunn) February 6, 2020
Gunn's gut was right in the end too. The first Guardians of the Galaxy movie opened to rave reviews and went on to gross over $772 million worldwide. Its success lead to the film becoming a full blown franchise, with Guardians of the Galaxy Vol. 2 outperforming its predecessor with $869 million worldwide at the box office. Its lead characters would go on to be staples of the Marvel Cinematic Universe and play integral parts in Avengers: Infinity War and Avengers: Endgame. A third film is also in development with Gunn set to step behind the camera once again, but a release date has not been set.
Not only was the filmmaker right about the film having the "color, fun, emotion, and characters" that people wanted in movies, it had what people wanted in other forms of media too. Following the success of the Guardians of the Galaxy on film there was renewed interest in them in the pages of Marvel comics, they lead an animated series on television, starred in their own video game, and even been the face of multiple theme park rides at Disney parks. The sky is the limit for the Guardians of the Galaxy, and James Gunn's confidence helped put them there.