This may not be much of a surprise but Hollywood really, really likes making money. Since blockbusters tend to bring in the most cash in the movie industry, studios are always eager to turn them into a multi-picture series.
Of course, this doesn't always work out. The first entry of Divergent, Percy Jackson, and The Chronicles of Narnia were profitable, so studios hoped they would turn into billion-dollar franchises. But after their sequels didn't fare well at the box office or with critics, each of these series were canned before they reached their intended climax.
But it could be worse. There are some franchises that turned out so badly, the intended follow-ups were abandoned after one single movie. Some of these failed series had tons of sequels, prequels, sidequels, and spin-offs planned and yet, they never saw the light of day. Occasionally, a studio will set up an entire cinematic universe only to cancel the whole thing after the first movie bombed.
Nevertheless, it is interesting to see what went wrong with these movies and how their sequels would've turned out.
20. John Carter
In Edgar Rice Burroughs' Barsoom series, a Civil War vet named John Carter gets transported to Mars, where he becomes an instrumental figure in a planetary war. Since the 1930s, Walt Disney himself tried to adapt the first Barsoom book, A Princess of Mars, into a feature. It may have taken decades but in 2012, the first film adaptation of the series, John Carter, finally hit theatres.
Director Andrew Stanton saw John Carter as the first of a trilogy and intended to adapt the sequel, God of Mars, if the first film was a success. The follow-up would've had Carter battling the Plant Men, have an epic sky battle with thousands of airships, and journey to Martian Heaven.
Despite failing badly at the box office, the cast and director still pushed to continue on with the second and third film. But when rights for the Barsoom novels returned to the Burroughs estate in 2014, the trilogy was toast.