The reason you have a spare is because you might need it in the future.
People seem to think that “spare” means that it’s useless, but it’s exactly the opposite. It’s “spare” because it’s useful to you. So it’s strange that people think you would give something away just because it’s “spare,” because that just means you’d have to acquire another spare for yourself.
Would you give away the spare tire for your car just because somebody asked you for it?