It’s not like Spotify is getting rich. They keep 30% and give artists 70% (although much goes to labels, but the point is that Spotify only gets 30%).
The market isn’t there for people to pay so much for music. It’s not unfair as much as a busker not being a millionaire isn’t unfair either.
How much money should someone get for a million people listening to their song? What’s the fair amount? I’m not sure, but I think Spotify is the closest artists have ever gotten given the historical payouts for radio, album sales, etc.
I think most of this is just people not understanding and naturally wanting more.