The "success" is not Spotify. I don't care if Spotify makes a loss or not. The "success" is that most people do not pirate music any longer but pay for it, be it via Apple Music and friends or via Spotify (even if the real bill is footed by investors).

Companies don't actually care very much about if people steal content or not. That's not the metric by which they are judged by their shareholders.

They care about if they generate profit or not. Minimising piracy is one part of that, but it's not worth destroying the rest of your business over chasing marginal returns on the anti-piracy front.