While I have sold stuff (almost all of my VHSes, for example), I've kept an extensive library of other physical media. I've had to resort to breaking them down though, they're too much otherwise, so I get why some would declutter.
That said, my comic collection still overshadows it from a sheer how much space it takes up. >.<
Unfortunately, I don't really trust streaming to provide something when I want it, and even though physical media has its perils (disc rot, etc) I'd rather risk that than playing hunt the show on through the streaming channels. And the more obscure stuff, they won't have anyhow.