Because when you have your own copy of something nobody is keeping track of what the date and time is when you watch/listen to that media along with how often you do it or what parts you view/hear more often or pause at most often, or where you are and what other things you are doing when you saw/heard it etc. You can enjoy your media entirely offline which is something you'll really want if you find yourself without internet access for some reason. In addition, you don't have to worry about that content suddenly going away without notice, or it being censored or modified at some later date. You also get the ability to play that media in your software of choice and can even re-encode the media to play on other devices using other formats. You can make your own edits. You can share your collection with others without forcing them to create an account and hand money/data to a third party. You can include things in your own collection that those third party streaming services might not approve of.

When you give up on owning things you give up a lot more than just the item you would have had sitting on a shelf or the file that would have taken up space on your hard drive. There are lots of freedoms and opportunities you gain that wouldn't be possible otherwise.

Because it might go away? My Youtube saved lists are littered with removed videos.

And I _do_ use a USB flash drive in my car of curated* music; it’s an always available radio station without and phone fiddling.

*curated= just Grateful Dead recordings

Your experience may vary, in my experience:

* things I've liked don't always stay on youtube or appear on spotify, and

* streaming|internet isn't always available (remote area FiFo, underground, etc.)

>why bother

You don't need an internet connection and don't have to worry about data caps or terrible jetliner satellite internet right then and there?

Not everything can be streamed. Streaming platform are applying censorship. Not everyone is signing in to provide their music to streaming. Also they usually stream not original tracks, but a remaster.

m4a*. Or Opus.

1. I don't have to pay a monthly fee

1a. I don't have to listen to annoying and offensive ads

2. I don't have to worry about something disappearing

3. I can listen to the version I want (remaster vs. original)

4. I can listen to music in the codec of my choice: <320kbps MP3 sounds bad, and some people prefer FLAC, for instance

5. I don't need an expensive cellular plan to handle all that bandwidth

6. I can listen to my music on airplanes

It's amazing this stuff is so hard to understand for people these days.