From the SlateStarCodex Reddit, an explanation of why Most of What You Read on the Internet is Written by Insane People:
I found one Amazon reviewer with 20.8k reviews since 2011. That's just under 3,000 reviews per year, which comes out to around 8 per day. This man has written an average of 8 reviews on Amazon per day, all of the ones I see about books, every day for seven years. I thought it might be some bot account writing fake reviews in exchange for money, but if it is then it's a really good bot because Grady Harp is a real person whose job matches that account's description. And my skimming of some reviews looked like they were all relevant to the book, and he has the "verified purchase" tag on all of them, which also means he's probably actually reading them.
The only explanation for this behavior is that he is insane. I mean, normal people don't do that. We read maybe 20 books a year, tops, and we probably don't write reviews on Amazon for all of them. There has to be something wrong with this guy.
So it goes with other websites. One of Wikipedia's power users, Justin Knapp, had been submitting an average of 385 edits per day since signing up in 2005 as of 2012. Assuming he doesn't sleep or eat or anything else (currently my favored prediction), that's still one edit every four minutes. He hasn't slowed down either; he hit his one millionth edit after seven years of editing and is nearing his two millionth now at 13 years. This man has been editing a Wikipedia article every four minutes for 13 years. He is insane, and he has had a huge impact on what you and I read every day when we need more information about literally anything. And there are more like him; there is one user with 2.7 million edits and many others with more than one million. . . .
If you consume any content on the Internet, you're mostly consuming content created by people who for some reason spend most of their time and energy creating content on the Internet. And those people clearly differ from the general population in important ways.