Out of the entertainment categories you just listed (porn, movies, music, books, games, sports) I think the porn can have the worst side effects on your life because it directly interfere with a relationship with your partner (many people go for porn rather then for sex with partner) or can demotivate one from searching for real relationships because porn is easier. And that can ultimately lead to worsening one's quality of life.
Do you have any credible, not thoroughly debunked research on this? I don't think anecdotes would be helpful here since most couples I know regularly commission porn of their characters and seem quite happy together.
Oh this actually brings up a whole other can of juicy worms: Forced monogamy.
Almost every culture guilts people into remaining in unsuccessful relationships and makes people feel like a failure if they have to break off a relationship.
Professional sports strike me as the same kind kind of aberration. People engaging in no physical activity while watching paid professionals playing sports via a long chain of technological and market devices. It even lacks the communal experience of actually going to an event.
A lot of the things we do and consume are poor, distant derivatives that barely resemble the real thing. Pornography is easily among the worst offenders.
I bring in technology because neither pornography nor professional sports as we know them today would exist without it. Colosseum was a rare thing, and it hosted live events with the communal aspect of it.
If you go your school league game, you're not doing sports but you hang out with people from your community. Modern professional sports are much like pornography: completely empty in both regards.
Books and movies retain their core purpose: storytelling. While pornography and professional sports don't.
It's like asking someone how can they approve of steak and disapprove of marshmallows. As if they were the same thing because they both provide some calories and can be eaten.
Porn isn't about storytelling. It's about sex. Otherwise it's just a story with gratuitous nudity and sex. And yet it lacks actual sex and intimacy. Making it a poor, distant ersatz.
Same with marshmallows. They're food, technically, but a poor, distant ersatz of a real meal. Both in taste and nutrition.
What about movies, music, books, games, sports?
Why do you think porn stars should not be treated like any other actor, artist, author, musician, developer, sportsperson?