Here is a bit of context to start with:
I live 150 km away from my little brother. My father got remarried to another woman, with whom he had my little brother (let's call him 'Marc'). Since we grew up together before I moved to continue my studies, I consider him as my brother instead of my step brother.
'Marc', since he discovered YouTube and gaming, is a huge fan of Minecraft and spends way too much time on it, at the point where it's getting obvious that he has an addiction:
He botches his homework assignment, which gives him really bad marks even though he entered middle-school and it's not hard at all to get really good ones
He barely washes himself, spending a couple minutes under the shower with no soap at all to win time and play more
He wakes up early on the weekends (8 A.M.) to play all day, without going outside at all.
My education through my father was way harsher back then, and I believe that he realized that and decided not to be this harsh with him, so he decided not to cut the internet or deny Marc's access to a tablet or a computer.
Of course, my parents have had enough with my brother's behaviour, and decided to cut the internet. He then starts a tantrum, answers back to his mother, and yells.
Last weekend, while my father called me to help him install some software, we talked about this and decided that I would go to my father's next weekend to have a discussion. He's worried but also overtaken by the events: he's approaching 60 years old and doesn't really know what to do.
So, since I'm going at their place next weekend, I'm planning to try to make my brother see how what he's doing isn't good for him and his family. I can relate, since I was an addict myself a few years back.
My plans are to make him imagine his life later if he keeps going like this, talk to my father about restrictions to set up (better marks to get the tablet / computer, etc...), but also to talk him into starting to learn web languages (I'm a web developer and my father told me that one time, Marc wanted to do what I do). This way, at least he'll learn things that might interest him and I could coach him even if I'm not around
However, my main concern is that he's just 11, and I know he'll struggle to see the big picture (having hard time to have a job without diplomas and such)
My main question is, how can I bring this whole thing to him with losing him?
Update: I got to see my little brother
I went to see him last sunday (as of 15/10/2017). Now it looks logical but he's not that "addicted", even though there still is a problem where he's prioritize videogames to homework, and I certainly can't blame him for this, since I did excactly the same myself.
We had a little discussion where I tried to be the least bit annoying, and well, I believe that he cared at least a little bit to what I said, I just hope this will make a tiny difference.
I set myself as the caring big brother (that I actually am), and helped him to do some english and french homework. We spoke a bit about development instead of playing, but for now he isn't really interested, I might try this again in a year or two, it will depends on if I feel he is mature enough.
Thank you all for your answers, an update was the least I could do. If it's still allowed, don't hesitate to comment on this and I'll try my best to answer you if needed