It's not really just Spotify. I'm a hobbyist music producer. I uploaded my entire catalog through Distrokid about two years ago. Distrokid serves just about every streaming service. It costs $20 a year for the most basic package. I've got ~8 million listens according to Distrokid, and that nets me about $40 US. So, I made my money back. Not bad for 20 years of work. Haha!
I don't really care about the numbers, like I said, I'm a hobbyist. I make music because I enjoy making music. It would never be my career unless I dropped everything and struck out touring trying to make it in an industry that traditionally chews up and spits out hopefuls. I'm not exactly the age or attractiveness that most people expect in a touring musician, either.