The Nexerus said
I've never understood why people torrent movies and TV shows. Why not just watch them streaming?
Because streaming can be problematic and torrents provide some options that streaming doesn't.
First there's the whole issue of finding a good site that's not just an ad-infested piece of shit that tries to bombard you with malware. Lots of people prefer to avoid that whole mess and hit a well known torrent site to get an upload from a reputable source, plus there's the bonus of there being comment sections available where other people can warn you away from garbage quality and virus-ridden files and such.
If you find an okay site, then there's the issue of quality generally being shit on streaming sites, especially soon after the release of episodes of shows. Anyone who's a quality snob would want to get actual 1080p video, and good fucking luck finding that up on a stream the same day as the episode aired, whereas it's available for torrenting for popular shows within an hour of the first airing.
Some people have spotty internet that makes streaming annoying as shit, since it's far more frustrating to watch a show as a stop and go thing with constant buffering. If you instead let it sit there for a couple hours with your garbage internet to load the whole video, well, you might as well have just done a torrent instead at that point.
Some people like having an actual transportable copy of shows/movies so they can watch them while traveling or in areas without internet access, or to throw them on their ipod or phone or whatnot. Similarly, some people like having a permanent copy that's not beholden to their internet connection and load times so they can watch it again later.
There you go, four solid reasons why some people prefer torrenting to streaming.