There's nothing movie fans love more than a healthy dose of speculation, with fan theories being the most creative form that speculation takes.
If you search hard enough, you can find theories on just about anything (looking for a connection between Pennywise and Harry Potter? You got it!), and it's generally quite fun to read over whatever crazy, intricate stuff people are able to come up with.
Of course, rarely is this stuff true - one of the most enjoyable things about fan theories is their outlandish nature, which usually makes them incorrect - and over the years, this has been pointed out by the people behind the films in question, with the creators essentially flipping you the bird, or telling you to stop being such a whimsical little snowflake.
Some of the most popular movies of all time have had their most prevalent fan theories debunked at some point, but on the plus side, it's interesting to hear filmmaking talent react to the ways people interpret their movies, even if they're only there to say those interpretations are wrong.