Years past humans would hear stories from within their social circle. These are important because they create bonds and pass on wisdom & knowledge from one to many. From this, humans gained a yearn for hearing stories, but without adequate restrictions anything that fulfills pleasure can and will becomes a vice. The average human will spend their little "free time" (another delusion) toiling as an observer to fantasies conjured up by individuals they have no connection or relationship with. Fictional media preys on your mind the same way a video game, or a coke, or any one of these artificial productions of the modern world preys on you.

It's utterly pointless and degrades one's life into voyeurism. Many don't think of this, nor think about the food they eat, the work they do, the "life" they live, they only think of the consequences if they become painfully visible. Even then you will see people unwilling to get out of the bond of slavery, and form lies to protect their habit just as an addict of heroin addict would.

Non-fiction can be as bad (biographies, documentaries), but (for the most part) it's primary purpose isn't a voyeur's pleasure, so it's rarely abused in the same way.