Stephen King's IT has been a beloved novel for more than three decades. The 1990 miniseries adaptation gained a passionate following. Audiences were excited for this year's adaptation of the novel. But not everyone anticipated it would go on to earn nearly $700 million worldwide. The author, though, knows exactly why the film became such a huge success. King told Entertainment Weekly, "I think one of the things that really happened was that 1990 miniseries.