What is a conspiracy theory that sounds like total nonsense until you actually look into the evidence?

For me, it’s the 'Dead Internet Theory.' The idea is that most of the internet isn't humans anymore it's just bots talking to other bots using AI to keep us scrolling. I used to laugh at it, but then I realized how many 'viral' videos have 10,000 comments that all say the exact same three phrases. It feels like we’re just watching a simulation of a conversation