When Google announced Play Music in 2011, I got in early and my subscription price was locked in at $8 USD a month. They gave me Youtube Premium (and Youtube Music) when that launched as part of that subscription. When Play Music was killed, my Premium membership continued at $8 a month.
At the moment, I’m fine paying this very specific early adopter price since I watch a lot of Youtube content. If they ever raise the price on me, it’s getting dropped.