It’s not odd at all to get your music almost exclusively from Spotify. It saves space on your computer because you don’t have to amass a huge collection of MP3s.
You can check out a new artist and decide you don’t like it without wasting $10, plus it’s easy to share music with friends and access your collection across multiple devices.
There are only two scenarios in which Spotify Premium isn’t worth the cost: you already subscribe to another music streaming service, or you only use Spotify a little bit each month.
If you already have a massive music collection and only use Spotify to check out a new artist here and there, you might not care about the ads or mobile access. In that case, Premium wouldn’t be worth the cost.