They’re called virtual currencies for a reason; they don’t actually exist. It’s just a set of consensus rules about who can make which transfers. The transfers themselves are just packets. To use bitcoin is to send packets containing signatures, nothing more.

Practically speaking, they can’t be anything but speech.

What you call it doesn't matter. If you can use it like a currency, it's property. Even if you can't use it like a currency but it's tradable at all, it's property.