Depends on what you mean by “own”.

Buying the CD has a key difference from Spotify in that no one can (typically) take the cd away from you. Music disappears from Spotify all the time. You can also (typically) copy it to other storage. And, most relevant to the topic of rent vs buy, you just pay for it once and you’re done. No subscription, no ads. That stuff is important to me.

You can’t usually take music you got from a CD and put it in your movie, for example, but that’s a whole conversation about fair use and copyright.