0. Ability to watch offline!
1. Ability to fix subtitle issues with minimal tweeks like change size or moving location.
1.2 Ability to get subtitles if they aren't offered (or offered in your language)
2. Ability to normalize audio.
3. Ability to buffer videos when on a poor connection.
4. Ability to create collections, organize, and track your movie as you wish
5. Arbitrary number of user accounts
6. Multicast streams to watch the same show across different devices regardless of if someone has an account or not (see JellyFin's SyncPlay)
7. No big organization tracking you and selling your data to the highest bidder
There's more, but honestly pirating is just a better experience. I can't tell you how many times Netflix has fucked up the subtitles so they are covering half my screen. There's tons of little issues like that that are just random and the only option is to just not watch Netflix (or pick your streaming service) that day.
Besides that, for the price of a yearly subscription you can build a NAS that can do all this for you and you get to keep the movies. Instead of having a monthly fee you can progressively add more drives and this can also be used for all your other things. Pictures, home videos, games (you can make a Steam cache), your local AI models, or whatever else you want. With $1k you can build a pretty good system, though that's 3 years of 4k Netflix, so not the cheap route in the short term.
