This is an excellent analysis; however there some points I wish to make:
1) The data for the BTC/USD exchange rate for 2009, and early 2010. I have managed to research this and found data for November / December 2009 and posted the results in this post
https://bitcointalksearch.org/topic/m.3309071 The valuation of .005 BTC /USD is way to high. The values ranged from 0.000614866 to 0.00130719 BTC/USD. Also the "pizza valuation" would place the BTC/USD rate at around 0.0028 in May 2010.
https://bitcointalksearch.org/topic/pizza-for-bitcoins-137. The net result of this is to significantly
underestimate the current trend and future value.
I am aware of that pricelist, but I discarded it because it is purely theoretical - no actual trade has occurred at those prices (afaik). I have based my estimate on the following nuggests of information that I consider reliable:
- I heard that "Theymos has purchased bitcoins at an all-time Bitcoin-OTC low of 0.003"
- I heard that the pizza incident (at about ~0.0025) was for a significantly cheaper price than commonly prevailing, to induce someone to make the effort
- The Norwegian guy bought
BTC5,000 for $27 (0.0054)
- The price 10-doubled when Mt.Gox opened (to 0.08, i.e. from 0.008)
Since I do not have a reliable OTC price history at my disposal, I estimated the whole time to be a flat 0.005. But if someone wants to add to the information, please do!
2) The exponential model works well only when the market penetration is very low say below 5% since it neglects the probability of a newbie attempting to introduce Bticoin to a veteran. Based upon the value of the world M1 money supply approximately 20 trillion USD and the world gold supply approximately 8.2 trillion USD I would say this model will start to break down between 50,000 and 100,000 BTC/USD.
If we were talking about penetration, the above would hold. But now we are talking about price, and very likely the price will overshoot before finding a long-term realistic value. This has happened before with Internet stocks - userbases have grown steadily but price has behaved erratically, first growing really quickly, overshooting, collapsing, and finding stability.