Remember though that there are two sides to every transaction. Given a consistently deflationary currency buyers become increasingly unlikely to be willing to offer said currency as payment to sellers. Thus the liquidity of the currency will tend to dry up, especially when it is does not have legal tender status. In a single currency market this is disastrous, in a free currency market you just start using something else.

Of course, the value of the now illiquid currency will eventually become highly volatile likely ending in a crash. Hopefully after this happens several times most people would get the idea that investment in such things is not a good plan.