Now that I have a streaming subscription to Tidal (CD quality) I find very little reason to look to alternative music sources. With Amazon Prime the same goes for a lot of TV and movies. But for niche stuff there will always be torrent sites.
Speaking only for myself, blocking commercials is probably the biggest motivator for myself in seeking DVD sets and/or series of TV shows. Once you have stopped watching "live TV" you'd be surprised how sensitive you become commercials blasting every 10 minutes. Kind of like turning off your ad blocker (I honestly don't know how people survive the web without those things). I'm willing to pay for the "privilege" of not being yelled at every 10 minutes...
(Well, added to my iTunes library, actually, but - you know.)
Edit: I mean yes, it's technically illegal but I've never heard of anyone being charged for personal use. And if it did happen the penalty would be a lot smaller because the damage done would be the price of a new blu-ray.
Most publicly available pirated content is terrible quality anyway. If there are shows and movies you really love it's worth it to make yourself a high quality rip. Emby/Plex are super convenient, especially playlists. Who wouldn't want their own private streaming service with all the content they love. The discs sit in the basement as disaster recovery.
This is where things are going IMHO.
Sometimes this has forced me to spend more money on drives/other storage (for example, I manually upgraded both my PS3 and PS4 to the largest capacity drives they support). And I have a NAS with a bunch of drives in it. Worth it, IMHO.