Since there are only ~20 million bitcoins, if 2 billion people are using bitcoins, the average wallet will have 1/100 of a bitcoin. How much would that buy, if translated in today's dollars?
You will not hear this from Krugman or Bernanke, and it is
the bitcoin secret, but only for you, my special friend, i can reveal:
It depends on what value those 2 billion people will want to have in reserve. Yes, if they first want it to correspond to a hamburger, the value will be just enough to buy 2 billion hamburgers. If they all change their minds and want it to be a week worth of living cost, it will increase in value to 2 billion weeks of subsistence.
Magic, say you? Try it out in your head, imagine that only the first person changes his mind. He will start to save, thereby depressing the price of the hamburger and at the same time marginally increase the value of the bitcoins. Then the next guy will do the same, reducing the price of the hamburger (reducing the value as measured in money), then the next guy... Since not everyone does this at the same time, the value increase will be unevenly distributed. Obviously, the first one will experience after some time that his savings have grown to be more than he requires, therefore he will spend to reduce it to the required amount of value while the process is still in progress. Roughly the same amount of hamburgers can be produced and consumed while the process is going on, and after it is completed. They consume the same, but now they are all rich.
That is what I call a better world.
