Within the last 2 years, I have sold approximately 40% of my collection. Mostly through specific audiophile and music lover forums. I do not use Discogs and Ebay. I try and sell by "bundling" to keep shipping costs down. The funds are spent on guitars and upgrading my audio system.
These days, I purchase and keep only what I deem as "essential" music.
A lot of what I have sold have been obscure and rare stuff. If your collection includes "Hootie and the Blowfish", Katie Perry and generally to 10 fluff, you are better off throwing it in the trash or donating it to Goodwill; no-one wants it.
Let's get some movement in there, people. 