It's absolutely cheaper in the long run for me. I spent a fair bit on my CDs (and digital downloads), sure. But I never need to pay another dime in my life. I'm going to guess that I spent somewhere around $1000 on my music collection. But $13/mo for Spotify for 60 years (if we figure one listens to music from 15-75) is $9360. I'm coming out quite far ahead by owning my music.

If you are someone who wants to frequently listen to new music, then sure, Spotify is cheaper than constantly buying new albums. But I at least don't do that; I listen to the same music I listened to as a teenager and I pick up 0-1 new albums per year. So again, no real advantage to using Spotify.