This is the "hyperdeflation" argument that we've already heard elsewhere. The thing about deflation is that eventually it has to stop, because there is a limit

This is the "hyperdeflation" argument that we've already heard elsewhere. The thing about deflation is that eventually it has to stop, because there is a limit to how much value all the people of the world can hold in any currency. People are buying bitcoins now and holding on to them, because they expect Bitcoin to be a useable currency in the future. It will become a useable currency when the deflation stops. (It is somewhat useable now for buying and selling, but taking taking out a loan in bitcoins is extremely ill-advised.) There may be some bouncing up and down before the value of bitcoins settles down to a somewhat stable final value. But it will eventually reach some type of equilibrium between the desire to hold it as a combination of desired savings (no longer held in expectation of constant hyperdeflation) and desired liquid "cash" holdings, and the desire to spend it, because sometimes there are things you want to buy. All this holds whether or not Bitcoin replaces all other currencies (which it probably won't). Whether of not Bitcoin hyperdeflation is bad for the world economy for some Keynesian reason is separate from the question of whether Bitcoin will continue to have value for its users.