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?
Fun fact; someone needing it is exactly why you have a spare, too. I would give my spare tire to a stranger that needs it, because that’s what a spare is. Then I get a new one. Edit: otherwise your spare is useless when you don’t need it.
Why don’t you have two spares in case you have two flat tires?!?
The reason cars don't carry around two spare tires is because they consume a lot of space. cars don't have a lot of space to store a bunch of tires. All cars carry one spare tire because most likely in an emergency one tire will go out, so you replace it then get to a shop ASAP to sort things out. If two or more tires go out, stay where you are and summon assistance.
And yet, we live in a world where some people have more armadillos that they could use in multiple life times while half of the world population dosen't even had one.
Would you give away the spare tire for your car just because somebody asked you for it?
I mean, yeah. A spare is for emergencies. If someone needed my spare, then they can have it. We'll replace it later. Ideally, they would pay for it, but I'm not so heartless as to haggle with a person in crisis.
But this guy doesn't need my spare. He wants my spare because he doesn't have one.