[loquor]

I too was like this kid not so long ago. Here are some perspectives.

1. THE CAUSE - How is he doing academically? I was doing really poorly because of lack of support, and to suppress that frustration I would try to stifle it with games, anime etc. So do consider that possibility that its a response to an emotional problem and not a deliberate decision. They may not want to indulge in media consumption all day, and it may merely be a way to reduce their friction against the world and themselves.

2. THEIR BACKGROUND - Some of the responses here suggest kicking out the kid as they're a legal adult. If my parents were to suddently ask me to step up massively at 18 and did so using force, I would resent it tremendously. Because since I hit my teens, they had long abdicated the role of supporting any personality development activity for me. So I would directly attribute my inabilities to them. Some of you would be aghast reading this, like how could an "18 year old adult" claim this. That's because I'm not American, there was a genuine lack of such opportunities during high school because all was forfeit at the altar of college exams. I actually still resent it a little that they didn't enroll me in something like the (Boy) Scouts, or a karate class, or a swimming class etc. i.e. avenues where I could get out and grow a little as a person. In hindsight, I've recognized that ny parents are people too with shortcomings, and I shouldn't blame them for everything because I can. That would be foolish and myopic. However, my point is that the parents were responsible kid's upbringing and environment growing up, so the resulting kid they have at 18 is their creation. (Americans wouldn't agree, I'm sure some Asians who grew up middle/upper-middle class would.) So its not fair to pin it all on the child. Punitive measures may be a bad idea. I much prefer what /u/WastingMyTime89 has suggested below, to sit down with your child regularly so that they open up about their issues and problems. In any case, opportunities for the kid to get out would be a great idea, both by themselves or with their parents.

3. GLOBAL TRENDS - I assume the kid is a male. I've observed the same phenomenon happening with a male cousin personally, wherein a boy doesn't grow into a being a young adult very well, and instead retreats into his room and anime/games/porn. I think Warren Ferrel's work might be a good start. It might be good to take a birds eye viee of the whole thing and be informed by other individuals ans how they self-improved.

P.S. of course, the kid in question may be quite different from what I've described. But if they are the trying-but-struggling type, you could give him a book called 12 Rules for Life by Jordan Peterson. It seems to have been fantastically effective for and well-received by many many young men. My 2 cents.