It's simple economics—with a bit of psychology thrown in.
Piracy reduces the effective demand for music, shrinking the market. Because the market is smaller, music writers, performers, and singers shift creative endeavors to cater to live shows rather than records. They take fewer chances and pander to a lower, (and broader), segment of the market. Additionally, artists are discouraged from getting into the industry by knowledge their music will be stolen. The result is more Ariana Grande and less Pet Shop Boys.
Want better music? Pay for it. Or better yet, invent a digital standard that is immune to piracy. A new system might be designed that uses quantum cryptography and a blockchain to deliver music to an app on your phone. You never actually receive the music file, but receive a digital key that entitles you to play it through the app, (and only the app), on your phone. The actual file is located in the cloud and streamed to your device. You can sell then key and let someone else play that music on their device, but you cannot copy it.
On an even more negative note, this is just one example of how you oppress yourself. Go ahead, read it. It's even more depressing. lol