Both Spotify and Netflix depend on content that they don't, and can't, own.

Netflix became a desert after WB, Disney and others decided they wanted their own streaming services and took their content with them. And since Disney basically owns everything, Netflix now has nothing (except their own content).

Spotify is fully at the mercy of the three-four big companies that own nearly all the music in the world: https://en.wikipedia.org/wiki/Music_industry#Consolidation

And don't forget, you also need to complete with companies with near-unlimited money and quick access to users like Apple, Google, Amazon