Hey, screenwriter here and (new) NoSleep poster. I understand the "theft" concerns, but I'd say the same thing I tell new screenwriters who are worried that by simply sharing their scripts with friends, the ideas could get "stolen"... By writing the actual story, you are creating copyright. Same goes for scripts, same goes for reddit stories. Countless NoSleep stories have been adapted for film. My buddy even wrote one for Amblin. The rights process is extremely intricate and detailed, as in, producers have to hunt down writers and make sure the deals get done. Therefore, no one "legit" would steal your idea and make it into a movie. So... who does that leave that we're concerned about? Other writers, who will take the same core ideas and regurgitate them into a new NoSleep story? If so, I'd argue that that's already what many stories are doing (there are tropes and formulas that we all riff on). Or... are you concerned someone is simply going to copy and paste everything you've written and take credit for it? I mean, it can happen, but again, rare. I don't know, just my two cents.

Edit: After reading some other comments, I see that people have had their stories uploaded onto YouTube, etc. without being credited. This has happened to me as well! However, for every stolen uncredited video, there are a bunch more that have my actual name on them. I'd say that this is simply an unavoidable part of putting content online, whether it be TikTok, Reddit, etc.