I have published some of music years ago on “feiyr”, where you pay for your music release once. I never have advertised the music at all. Back then it was just a test, if this really works.
Here is the result:
You can see that Spotify pays you 0,002€ for one play.
Is it really worth it, it’s another question, but let’s scale this up:
Let’s say we want to have 300€ on side every month from Streaming, how many plays do we need to have?
1 play = 0,002€
150.000 play = 300€
As long as you not “TwoStepsFromHell”, it’s basically impossible to earn some money through these kind of Streaming-Services! These services are made for making money for the guys, who made this model and for your “Advertisement and Joy”, so you can say, “Hey, I am cool, because I have music featured on Spotify and Co.”…
What I do now, I went back to BandCamp and offer my music there. Yes, the guys get 15%, because they holding my music on their server, but 15% is not 50% like iTunes, where people can max. hear 30s of your music, if they are interested, plus you need to have in mind, that the distribution-sites will cost you another 15-20%. So like on my list, you sell one track for 1,29$, but at the end you will get only 36¢ back, is it fair? I don’t think so. You almost lose 1$. You make them rich, not yourself at all. But this is only my opinion.
But as I said: You decide if you want to have your music worldwide, so “fans” can find you, or you just have it on bandcamp on your own site.
Hope it’s more clear now, what’s going on in the Streaming-Business 
Best regards,
Alexey
PS: Forgot to say, I think it’s ok, if you just stick with some streaming-services, but don’t offer it on iTunes and Co. If a fan will like your music, they will find your music exclusively on BandCamp. Or you can make your own shop on your site, where you get ALL the money.