I think the thing that's stopped me falling into any major new fandoms is that the new ones tend to be shorter lived. there are far more shows now, and hence fans move on rapidly to the next one.

there isn't the time to get into the sheer depth that I did with Blake's 7 fandom. I must have been immersed in that for at least a decade, and most of my long term fan friends still date from that era.

I'm unlikely to watch a new show unless one of my friends from that time is also into it and recommends it.

But I almost never write now. I'm the kind of person who likes to burrow down. I want to do stories with no continuity errors, deep background and interesting new (but accurate data). That takes time. Why make that commitment when half the fans will have moved on before I've finished it?

I'm currently putting an equivalent amount of creative effort into an RPG I'm playing, which is mostly text based between the players. I've created an entire religion (based on Polynesian traditions), and there's only two players who will see the depth of what I'm doing. But they really appreciate it, and are developing their own detailed backgrounds which I am enjoying. Without feedback, there is nothing.