I'm not going to post to the satanic link, but when I typed witchcraft into Amazon I got over 11,000 books. None of the most popular ones had anything to do with Christianity. So if there's obviously a non-Christian market.
Satanism brings up 1,600 titles, again, non-Christian market.
But you're right, we're fools for believing these people exist
Obviously so is Amazon, printing books that nobody is buying.