What you’re describing is data hoarding. I pirate a ton too, but you know what I do with a movie or TV show after I’ve watched it? I delete it. Poof, gone. But it’s still in the most important dataset I have. My memory. To help with the metadata of my own memory, I write down a list of the films I’ve seen. I only keep the movies I really love and want to rewatch (Robocop). That TV show I just finished that was great…
I rewatch things all the time. If I’m doing side work at night and just want something on the background I’ll put on a movie or show that I’ve seen before. Beyond that, hard drives are cheap! I have a single 18 TB disk in my main computer that runs Plex. It lets me and my kids watch content from anywhere with an Internet connection. 18 TB hard drives are about $300.
Resilvering might take ages. So long that raid2 might be mandatory.
I haven't calculated the right risk factor but I still only use 4tb disks