Despite that Nikke (above) is working hard to find out the objective figures concerning the number of users, I will post new results that pretty much assume that the number of users is 1.0 million (discussion upthread after the Mt.Gox numbers came out). The new information is in the distribution parameters that were updated based on the Mt.Gox data.

22. Apr 2014

#People	#Bitcoins	#TotalBitcoins
70	BTC10k+	3.6M
930	BTC1k-10k	2.2M
13k	BTC100-1k	3.0M
85k	BTC10-100	2.3M
250k	BTC1-10	0.8M
340k	BTC0.1-1	0.1M
230k	BTC0.01-0.1	0.0M
90k	BTC0.002-0.01	0.0M

Total: 12.2M bitcoins (0.5M bitcoins assumed lost)

The changes from previous estimate:

- Total number of holders revised down from 2.0 million to 1.0 million. This did not change much in the distribution of coins. If new users are added, the large holders do sell according to an experimentally derived rate of 17% per doubling in price, but some newish holders also add to their positions. All-new entrants can come to any bracket, because no amount of coins is yet too expensive to buy. The perceived static totals of the analysis hide the fact that Bitcoin trade is quite brisk and the people who consist of a bracket do change all the time.

- Number of 10k+ holders recalculated because we now know better the average number of coins in each bracket (thanks to Mt.Gox data). So the large holders still have the same number of coins in total, but there appears to be more of the holders.

- Same for 1k+ and 100+. More people but approx the same number of total coins.

- 10+ category turned out to be larger than previously estimated. The Mt.Gox data gave us the confidence to use a steeper j parameter, which means a more "equitable" distribution with more coins in the middle brackets.

- 1+ category remained intact, and the fractional categories were significantly sized down. The lower threshold of "owner" was also raised to BTC0.002 because of the decline in price.

- Number of Bitcoin millionaires at this price ($500) is about 400. This means that only 400 people worldwide can raise a $million by selling bitcoins, but about 30,000,000 people can invest a $million to buy bitcoins (without going into debt).

- The Bitcoin millionaires command about 4.9 million bitcoins, which is 40% of all bitcoins. The control of world's gold and fiat currency is more centralized with a smaller number of individuals controlling higher percentage.