I don't download torrents but because I'm on a CG-NAT connection, I now know what kind of pr0n one of my neighbours is into. I could probably have done without that. :-|
Same here. A lot of Porn. Why are so many people torrenting porn? If there's one kind of Media that's ubiquitous on the free web it's porn.
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.