People are generally not that good at restricting their emotional responses to interactions with real world consequences or implications.

Here's something one of my psychology professors recounted to me, which I've often found valuable to keep in mind. In one experiment on social isolation, test subjects were made to play virtual games of catch with two other players, where each player is represented as an avatar on a screen, and is able to offer no input except for deciding which of the other players to throw virtual "ball" to. No player has any contact with the others, nor aware of their identity or any information about them. However, two of the "players" in each experiment are actually confederates of the researcher, whose role is to gradually start excluding the real test subject by passing the ball to them less and less, eventually almost completely locking them out of the game of catch.

This type of experiment will no longer be approved by the Institutional Review Board. It was found to be too emotionally taxing on the test subjects, despite the fact that the experiment had no real world consequences, and the individuals "excluding" them had no access to any identifying information about them.

Keep in mind that, while works of fiction such as books and movies can have powerful emotional effects on people, they're separated from activities such as the AI box experiment by the fact that the audience members aren't actors in the narrative. The events of the narrative aren't just pretend, they're also happening to someone else.

As an aside, I'd be wary about assuming that nobody was actually affected when you said things like "I hate you" or "you are a bad person" in pretend contexts, unless you have some very reliable evidence to that effect. I certainly know I've said potentially hurtful things in contexts where I supposed nobody could possibly take them seriously, only to find out afterwards that people had been really hurt, but hadn't wanted to admit it to my face.