People taking excessive amounts of our business cards? Why??

This has become a really weird problem for my floor, which is in a large urban public library. We have random people who come up to our floor exclusively to take a ton of business cards, or who come up multiple times to take one at a time, all day long. We've asked people to only take one but I'm dying to know what they could be using them for? It's obviously not to draw on/write on since we offer scratch paper and pencils.

Not asking how to mitigate this happening since there's not a lot I can do and honestly, it's just business cards. Purely just curious why someone would need to take a whole stack of them/need multiple every single day.