@dacoinminster, i believe you keep making the same analytical mistake, which is to be estimating the size of a 'market' and assuming that that size directs the fundamental value of a bitcoin. in the way you seem to want to be analyzing the fundamental value of a bitcoin, the proper measure is instead the demand for a bitcoin in equilibrium.
as a test, consider: what would prevent the scenario you describe (which is unlikely anyway for all sorts of reasons, and is actually not novel with you; there were discussions about it months ago) from being done with bitcoins that are at a tenth of their present value? a hundred? ten times? a hundred times? you're telling a story about fundamental value that is entirely orthogonal to fundamental value. it would be like saying that the price of hard disks has to increase because of all the new bandwidth devoted to youtube and bittorrent.
the fatwallet discussion gets this right, at least in concept.
http://www.fatwallet.com/forums/finance/1090435/m15946753/#m15946753. you can plug in whatever figures you want to that kind of analysis, but at least it gives a good way to think about it.
as to the specifics of what you're saying, bitcoin is probably not anonymous enough to achieve it, and it's not clear there's enough demand for it. pretty anonymous betting and bookmaking institutions exist in most developed countries outside the united states, and they haven't taken over the economy or caused those countries' currencies to skyrocket. the fees for more mainstream transactions are already not very high, and most large traders don't care much about anonymity (or even the pseudonymity bitcoin provides).
the more typical story of bitcoin as a potentially useful payment system for goods and service is both more compelling and more realistic.
If Satoshi had designed bitcoins to stop at 21 billion, instead of 21 million, bitcoins would be worth 1000x less. If that's what you are saying about whether this is possible with cheaper bitcoins, then I agree with that part.
The equation I use is two parts:
1) How many USD are going to try to go into bitcoins?
2) What percentage of bitcoins are not for sale at any price (in the near term)?
The facts that I see driving stock traders towards bitcoins are as follows:
1) Cost per trade could theoretically be pennies instead of dollars (order 100x cheaper per trade)
2) Possibility to trade in ways that don't currently exist (like betting against stocks that have no shares available for short-borrowing, and have no options or futures contracts being traded - there are a huge number of little stocks that fit this description)
3) Possibility to trade anonymously (can you explain why you believe bitcoin is not anonymous enough for this?)
4) If designed correctly, there would be no central server which can be shut down to stop the trading activity
5) Ability to design and publish my own bet, on any security I want, and wait for somebody to take me up on it
Perhaps I haven't looked hard enough, but I haven't been able to find anyplace in the U.S. or outside the U.S. which offers even one of these advantages.
No matter what assumptions I make, the number of USD going into bitcoins always works out to be "at least a few billion USD". I doubt if half of the bitcoins in the world could be bought up, no matter how high the price goes, at least not in the near term.
It may be a long time before somebody becomes a trillionaire because of their bitcoin holdings, but I believe that bitcoins are more likely to bring about the world's first trillionaire than any other economic force I can think of.