In January 2015 Coinbase said they passed 2 million users, NOT UNIQUE.
"The question though is whether or not the accounts represent human beings or if there are a lot of duplicate or dormant accounts."
How many of those accounts were created, used once, and then abandoned? The number of actual bitcoin users I expect to be much lower.
2 million users and 2.6 million wallets is what they cite. so 600k are not unique wallets.
There are only 1.8 million addresses with a balance over 0.001 (26 cents). I think this number is a better representation of users vs how many accounts coinbase has opened.
Where are you getting this number from?
You are aware that many wallets with bitcoin exist off the chain right? I have personally given 40+ of my friends and family members 40 dollars or more in bitcoin with services like coinbase which are held off the chain and only a few of these have bothered to get a unique public address. Additionally, all changetip users are holding off the chain accounts as well.
https://www.cryptocoinsnews.com/bitcoin-exchange-coinbase-just-passed-2-million-users/bitcoinrichlist.com
I don't think you count those people you sent money to on changetip unless they actually still use bitcoin. You have to think about those who opened a coinbase account just so they can cash out their changetip they received and have it deposited into their fiat bank account.
What about those that jumped on the train in late 2013 and created an account, and then stopped using once they didn't get rich over night?
If we're going for total historic number of people that have ever tried bitcoin, then maybe we'd be at the 4 million number. But total number of active users has to be 1 mill or less in my opinion.