The book nobody borrowed may still have mattered to the person who knew it was there.

A book nobody borrowed can still have mattered enormously. Its presence on the shelf meant it was there to be found, and the possibility of it did work for people who never took it out. Availability has value that circulation figures cannot see.

This is a reason to be careful with what gets cut for lack of use. Libraries, services, options, and skills often function by existing rather than by being used. And it is worth applying to yourself: some of what you keep and rarely touch is doing quiet work as a possibility, and that is not the same as waste.