I don't think it's quite that bleak. I admit I don't know the exact age range of your younger brother, but I think a lot of us here used to watch dumb YouTubers/Twitch streamers and think it was deep and meaningful content, only to completely lose all interest and realize how bad it was once we grow up. I feel like that's the case with a lot of Hasan's viewers, he tends to have a primary demographic of younger people, but but he cycles through them. As more come in, the ones who have aged up start catching on to how meaningless his content is and leave. And then, ideally, the crowd that left will recommend other people towards someone else. It's not quite enough to break the cycle, there's always going to be a new wave of younger viewers, but it does diminish it a tiny bit. And eventually, they either fade into obscurity, or ultimately make it big enough where they can go off to do something else that allows them to more passively collect income.
It's hard to say which will happen to Hasan. I'll give him the faintest bit of credit and acknowledge he seems vaguely aware he should try and branch into other things, but I'm not sure if that's because he's thinking about the future or just craves more attention. Given how dependent he is on his looks, if he can't find something behind the scenes to do, he'll be screwed when he's aged too much for his fans to continue pretending he's some kind of chad himbo. Again, I don't think he'll ever die outright because he'll have enough loyal fans keeping him propped up as he spergs about politics, but it'll be a shadow of the numbers he has now.