There are many other ways to compete on rather than just pricing. That 30% less can be recovered by having exclusive artists, a better product, and a stronger presence on other platforms.
I don't see how having exclusive artists (or even content) encourages bad competition. These are artists/content that potentially wouldn't have existed without Spotify's investment.
A stronger presence on other platforms would enable Spotify to make more revenue from those users vs. what Apple could siphon. Apple's main focus is on iOS. Furthermore, Apple Music's association with Apple probably hurts its image on other platforms like Android, giving Spotify an edge.
What I'm inferring is that Spotify can easily make up that 30% loss to Apple with other tactics just by differentiating.
