Hmm! He might have things going on along with the ADHD. One thing I know about video games and ADHD is that they’re a highly stimulating activity, and something that’s highly stimulating is needed to wake up our ability to focus. I don’t ever remember swearing at my videogames or being inappropriate with my family when I was bored, though. He may have another thing he likes- contrary to many with ADHD, I was super into reading when I was a kid and would be up until 2am reading horror stories to keep the adrenaline going. I know it’s problematic where sleep is concerned but there wasn’t much I could do about that. I remember horror books being so engaging to me that I’d have to sneak flashlights into my room because my parents would yell at me if the lights were on. I’d read them during school. If he has a set of thrill-seeking behaviors maybe he can be redirected to something non-destructive like that. Not sure if that is a perfect example as many people with ADHD don’t like reading, but redirection can help.
The inappropriate behavior and verbal abuse toward his mother needs to be addressed clinically. I have many problems that are clearly rooted in ADHD but I wasn’t terrorizing my family like that in my childhood (or now,) and one should expect that he act appropriately with regard to his family. While engaging in stimulating activities is normal, engaging in immoral activities is showing a lack of understanding how other people are feeling. Try using statements with him like “when you look at people while they’re in the bathroom they feel disgusted and unsafe.” And also he needs to be in a clincial office.