Dead weight
An unused book isn’t very useful. Neither is an unused couch.
It doesn’t matter how much you paid for it, how many years it’s been in the family, or how ‘valuable’ it apparently is.
An unused object is still a useless one. Kind of like a tree in an uninhabited forest.
If it’s useful, use it. If not, don’t. Just don’t trick yourself into believing your junk is anything other than what it is.