This shows current number of users and many more interesting statistics!!
An academic research, not based on just estimation but based on a lot of facts and collaboration with the exchanges etc. Copying highlights below in case you do not like to read the pdf
KEY HIGHLIGHTS OF THE STUDY
•The current number of unique active users of crypocurrency wallets is estimated to be between 2.9 million and 5.8 million.
•The lines between the different cryptocurrency industry sectors are increasingly blurred: 31% of cryptocurrency companies surveyed are operating across two cryptocurrency industry sectors or more, giving rise to an increasing number of universal cryptocurrency companies.
•At least 1,876 people are working full-time in the cryptocurrency industry, and the actual total figure is likely well above two thousand when large mining organisations and other organizations that did not provide headcount figures are added.
•Average security headcount and costs for payment companies and exchanges as a percentage of total headcount/operating expenses are similar, but significantly higher for wallets.
•The exchanges sector has the highest number of operating entities and employs more people than any other industry sector covered in this study; a significant geographical dispersion of exchanges is observed.
•52% of small exchanges hold a formal government license compared to only 35% of large exchanges.•On average, security headcount corresponds to 13% of total employees and 17% of budget is spent on security.
•Between 5.8 million and 11.5 million wallets are estimated to be currently ‘active’.
•The lines between wallets and exchanges are increasingly blurred: 52% of wallets surveyed provide an integrated currency exchange feature, of which 80% offer a national-to-cryptocurrency exchange service. In contrast with exchanges, the majority of wallets do not control access to user keys.
•While 79% of payment companies have existing relationships with banking institutions and payment networks, the difficulty of obtaining and maintaining these relationships is cited as this sector's biggest challenge.
•On average, national-to-cryptocurrency payments constitute two-thirds of total payment company transaction volume, whereas national-to-national currency transfers and cryptocurrency-to-cryptocurrency payments account for 27% and 6%, respectively.
•70% of large miners rate their influence on protocol development as high or very high, compared to 51% of small miners.
•The cryptocurrency mining map shows that publicly known mining facilities are geographically dispersed, but a significant concentration can be observed in certain Chinese provinces.