Bitcoin could have around 1 to 5 million users in 2020. But that depends on the infrasture of the bitcoin being built.
I think bitcoin has currently around that number and personally I am expecting it to rise due to the rising price which attracts more people who will in turn cause more price rise. It is like a loop and will continue as long as it is let continued. Usually someone just organize some kind of temporal crisis that will make people panic selling their coins and the price drops (like Gox).
Bitcoin is currently on 3 million total of users.
(Check it here: https://www.reddit.com/r/Bitcoin/comments/2vuvxs/estimated_number_of_bitcoin_users/)According to
amnesiac-eightyfourBitcoin owners: probably 2-3 million
Bitcoin users (actively spending, trading, following news): 200k-500k
The (pseudonymous) character of Bitcoin doesn't allow us to make exact figures, so all figures in this thread, including mine, are just guesses or assumptions.
I think in the end it's not so important how many people use Bitcoin. More important is if the infrastructure is getting stronger and if the network activity is growing. I think all indicators show that's true.
Your estimation might be true.
However, I think Bitcoin will more likely increase in adaption rather than stay stagnant or decline. Increased adaption with only 4 % inflation rate with extreme scarcity of number of coins must drive the price up.
I think the only thing which could stop the adaption and crash the price all the way to 0 is some technical issue which will not be solved.
Bitcoin has billions of potential users, and that base increases every day along with population growth. That is the equation why I think bitcoin is still in early adaption phase and everybody reading this can be a pioneer by buying as many bitcoins as you can afford. Try to increase your share of the pie before the masses will find bitcoin out and buy in. That will be madness and even holding 1 bitcoin make you extremely wealthy (getting 0.1 btc will be very hard).