I joined because Reddit has become a cesspool of bots and toxic behaviour. Lemmy is still completely open-sourced, while Reddit isn’t at all now. Also, when you first sign up on Reddit currently, you get completely ignored now and can’t post or comment on regular subs.
I joined during the API blackouts, wanted to show some solidarity by not using Reddit during that time.
Then stuck around because I liked it. Though I’m still on Reddit too.
I’m not on Lemmy though, but I know you mean the threadiverse in general. I’m on Mbin.