For me it’s preparing for future nostalgia, I want to be able to just "have it’ to look back on. It may sound strange to some people I guess but I can’t properly get “invested” in a show/movie/game without the knowledge that I’ll be able to rewatch it again, maybe at some point when I’m in my 80s and feel nostalgic about it. It’s a major barrier to my enjoyment in the present. It’s like why people take photos of things. 99% of what I would torrent are things I have access to now, that I would happily pay through the nose for if I could just own it in a DRM-free format.