A lot don't care if it is. I've had friends share things and I stopped replying with "you know this isn't a true story/fact/real image, right?". Their response is always "idk i thought it was funny/interesting" which is valid. I felt like I was raining on parades so now I usually just respond with an emoji.
> "idk i thought it was funny/interesting" which is valid
Ha, I don't know your friends but in my experience that's like a textbook phrase people use to try to play off being duped when they're clued in
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The problem is though that even if they "just think it's funny", over time it gets built into their worldview.
It's like people who only consume TV shows and movies, they know it's all fiction, but if you talk to them about how the world works, you realize that all their mental structures are based on Hollywood tropes.
This even tracks to reddit, where everyone knows it's bullshit and reddit is dumb, but their entire perception of the world is still reddit's dumb views anyway.