Well, it's just my collection - partly from my many, many CDs, partly stuff I bought online. I obviously don't listen to all of that every single day, but I wouldn't want to delete any of it either. So that's kind of a dilemma, because I also have 20-30 gigabytes' worth of photographs. Even if I get an expensive 256 GB SSD, I'm already constricted (and one shouldn't fill SSDs up to the brim).
It's a crying shame that the music industry, or one of the digital delivery providers (Apple) hasn't come up with a proper DRM solution that includes a central repository for your music licenses. Would be nice for you to be able to register your purchase (existing CDs) etc with one place, then be able to download the content on demand rather than being forced to keep it all stored on your machine.
Personally, I'll be keeping my music on a USB drive, or possibly on a HDD if I elect to remove the optical drive in order to attain more storage.