Spotify don't invest in music. They invest in podcasts and such like. Their "investment" in music amounts to the fake artists, designed to essentially reduce the amounts paid in royalties (i.e. - the fake artists need to be paid too). For ease: imagine that Spotify have £10,000 in royalties to divide up among 12 artists. If they invent a further 4 artists, the £10,000 the same because it's based on subscriptions but it is now being divided among 16 artists, except, for 4 of them, the money goes straight back into Spotify. The 12 real artists earn less than they would have done.
Apply that at scale to the numbers Spotify actual deals with. They are paying one-off session fees or buyouts with a huge return, especially on ambient/relaxation/etc playlists, all the time whittling away at the viability of music as a full-time income. Short term gain with long term impact.