Quality and rarity. There's better quality Asian stuff in torrents than on the web. 4chan.org/t/ has a lot of threads like this

Water is ubiquitous in the Atlantic Ocean but it's salty and full of fish poop. I drink water from my kitchen faucet because it's filtered and treated freshwater that is pristine and tasty.

A lot of people are collectors with way too much time—among other things—on their hands.

Quality. You're not getting hour-long 4K60 videos for free legitimately.

Increase ratio in semi-private trackers ? More often that not your download quota is linked to your ratio.

Because porn disappears