We know that parts of our minds think scary stories are important because our minds find them important enough to dream about. If scary stories are important, then we are compelled to experience them.
Sometimes the news will cleverly play on our hopes and fears one after the other, with a headline or teaser like "is your child being mistreated in preschool? Find out what you need to know." Like religion, the news scares you and follows up with hope for a solution.
Sometimes the news caters only to hope. No doubt many readers have heard that having a pet increases happiness and health. But few know that the studies reporting no effect are just as numerous. A study showing no such effect is something nobody wants to read. It's not scary nor hopeful enough to grab anyone's attention. It's in the boring dead zone, the anti-sweet spot. As a result, in this case only the positive gets reported.
Like a lot of news, contemporary legends (popularly known as urban legends) tend to be scary. That is because the scary ones are more likely to be retold, as was found in an experiment by psychologists Jean Fox Tree and Mary Susan Weldon. According to my theory, we find cautionary tales compelling because of fear and hope.
The middle section of the article also gives an interesting reason for why people find slot machines so addictive. It comes down to our brains being stupid and telling us "Hey, you're getting better at this. You got really close to winning that time. I bet with more practice, you can get a win on your next pull.".