It may not be a currency, but it is wealth. It doesn't really matter what currency they use as long as they can acquire enough of it to make the trade.
Discussion
Wealth? Needs a 'shared value' and an equivalent to it, no? Might be I'm too stupid for anything else but Bitcoin by now; the oracle, the dominator all not solved there.
Real wealth is resources. Money is just a measuring stick of relative value that assists in the exchange of goods. Money isn't in and of itself, wealth, if it can't be used to purchase what you need.