It may be that they're looking to create a monopoly and price competitors out of the market, and will raise prices (but probably not payments) when/if they succeed. Or perhaps they have already? I don't know of a real competitor to Spotify.

Edit: by real competitor, I mean one that most people will know and hence, can compete. Even monopolies like Google and Facebook have competitors that some random person I ask is likely to know about. Not sure I could say that of Tidal et al.