Regardless of pricing you can't substitute one with the other... Spotify is a streaming service with a massive library. Self hosting means you must BYO media... and, news flash, populating a library with relevant content that rivals Spotify or would satisfy your average user will almost certainly require illegally acquiring said content.

Youtube has much more music than Spotify, is better sorted by Albums (without holes, no skips) and you can easily rip it. It has all the better obscure artists, Spotify delisted.

There's also a recommendation engine via YouTube Music.

And once you start listening there, your video suggestions feed becomes a music feed thus degrade the video experience. Vids and music must be separate

I am a heavy YT user and recently started using YTMusic and noticed no change in my main feeds.

Well, their video suggestions suck anyway. I'm fine with music and table tennis alone

Ripping from YouTube is piracy. Again, what OP is suggesting really only works if and when you build out a large library through piracy.

This is my bottleneck too. I'm all for paying artists, and the hustle of setting up self host doesn't bother me (maybe not for my wife though, who is way less tech-y than me and is in my spotify family plan.) But the benefit of tens of millions of music, a search away, is simply too much for me to give up. I do my annually retrospective in music, and Billie Eilish was my back-to-back favorite artist of the year. Without streaming service, I probably wouldn't have tried her music at the first place.

I like that I must bring my own media. It means everything on my server was intentionally put there by me. No extra shit.

You don't need to rival Spotify's library. How many songs on spotify do you have added to playlists? You just need to purchase those....

I'm probably listening to more music than the majority of people, but I have about 6,000 songs on mine.