national currencies are not store of value, you're right. From my pov they're not money. exactly because of that they can be printed cheaply. gold was money, bank notes backed by gold were money, anything what can't be easily inflated can be money. this property makes them store of value. because if I transact with you I want something what guarantees me that it's value won't disappear and I can use that to buy what I want the next day. same thing is savings (which is a different word for hoarding). I don't spend (everything) because I expect goods will be cheaper in the future (either same thing will be cheaper or there will be a better equivalent; e.g. computers or washing machines, cars. look at their prices/value 20 years ago relative to your purchasing power) but I digress...