"Money" or "currency" is, as I see it/feel it (it is 2 am and I have had some alcohol) is an esoteric system which society has created and bought into essentially so we may assign specific and mutually understood values to, essentially, everything.
I wouldn't say money is supposed to be a store of wealth; "store" implies a certain inherent static intent and purpose engineered into currency at creation. I don't believe anyone came up with the concept of a currency with the sole or even primary intention of then hoarding it; money is created so that people may trade and barter. Money is a quantifier.
Money can be a measure of wealth; but in and of itself I'd argue it was never supposed to be a store of it. In a one-man society money doesn't exist, but a one-man society can store and stockpile all sorts of goods and valuable items. Money is a form of communication almost. It only exists when two people or more want to exchange things (different things).