You've got it understandably wrong as it's actually made up of grown adults but acting as if they were 13 year olds. It's an important difference if you think about it.
I wasn’t kidding, it’s truly full of 13 year olds. There are certainly grown adults, but I don’t think people don’t realize how many kids use 4chan. Back when I was a teenager, I thought I was cool as fuck for knowing about 4chan and all my e-friends were just as deluded and 14 as I was.