What I am looking for is the simple number, of fiat, converted to USD, that people have used to just buy bitcoin. I've heard guesses ranging from 100 million to 8 billion. The number doesn't need to be correct, but you can think about it like mutual funds.
If it doesn't has to be correct, why not simply use market capitalization in USD (number of coins in cirulation X market price)?
Even if part of that number is the result of direct purchases of goods with Bitcoin (without converting to fiat), the number will likely be higher by the time you publish your research...
I think all other guesses can't be reliably verified to be any more correct.
ya.ya.yo!
you cant just use the number of coins in circulation x market price.
as those coins may have swapped peoples hands 10 times in just a year.
for instance btc-e trades about 5 million coins. then last year mtgox was trading about 18million coins, bitstamp about 15million coins. coinbase, then add bitpay, cryptsy, cryptorush, mintpal and the other 15 crappy exchanges. your probably looking at 50 million coin movements WITHIN AN EXCHANGE.
which would equate to about $20billion ish
without knowing how many of those coin movements actually resulted in a bank deposit or a bank withdrawal, because most of the time the coins and dollar just sits in the account while people play around with SQL data base entries daytrading orders.
all that we can know for sure is that it is well OVER $20billion a year worth of coins is played around with and maybe over that. then as i said in my last post multiply that by the 4 years where volumes may have been less. your probably looking at 50billion just in exchange movements on sql databases.
but only the exchanges themselves would have the answer to how much physical money entered and left the bank accounts.
you might be looking at well over 100million coin movements where roughly 50-70billion is total bank account movements over 4 years of all bitcoin activity, once you include everything from exchanges to other swaps(merchant product sales, VC investment, private exchanges, localbitcoins, otc and other professional exchanges, advertising, paying wages, etc, etc, etc)
after all most of the exchanges day trade without bank movements, but private trades are more about direct bank transfer purchases, along with the other stuff i just wrote in brackets.
again to clarify
exchange internal movements 50-70billion
other swaps internal movement 30-50billion
=
exchange dollar transfer 20-30billion(actual bank account movement)
other swaps dollar transfer 30-40billion(actual bank account movement)
but all we can do is guess via limited information available
but i stand by my rough estimate of over $100billion internal transactions and atleast $50billion result of actual bank movements