Spotify rents music that it itself rents from 3 companies that own most of the music. Why would those 3 companies not just raise their rents if Spotify starts making a decent profit?
Spotify has been around since 2006 and just eked out a tiny profit last year. Unless they plan on owning music themselves, I don’t see why the music owners wouldn’t try to capture most of the profit.
Which still isn't a useful comparison.
One is an outright purchase, and the other a subscription service.