And dating addicted gamer that also drinks or takes drugs sounds like special kind of hell. It would just make her suffer in bad relationship where she has no meaningfull companion and partner.
No girl can cure any of these. And guys like this won't change after starting to date a girl - not for long. The idea that she will civilised him by her presence is bonkers.
Hardcore gamer culture is not the "you found a girl stop playing that much" culture. It is "you don't play enough you are weakling get gut looser, if girl stopping you from hobby she is bad partner" culture.
Amd real life dating activities are boring compared to excitement of gane for gamers. Even if he wanted to stop instantly, it is trully hard.