Have you ever sat in front of a casino's slot machine. They are also trash, awful and disgusting. But they're also engineered with the worst dark pattern psychology to manipulate any human being that sits on it to keep playing and be so addictive that people will burn their money just to keep playing. The qualities of fun, and additive are independent of each other. A game can be very addictive and really bad at the same time. Unlike slot machines, they have the advantage of constantly sitting in your pocket and going with you everywhere you go.