Bitcoin was launched in January 2009; it was both the first cryptocurrency and the first blockchain. Bitcoin, as trustless and censorship-resistant money, was the only blockchain “killer app” for many years.
And third, the user base had to grow over time; the more people that use email the more valuable it is to each user, and this virtuous cycle of adoption takes time to play out. In 2013 we saw the first hint of broader adoption as companies like Coinbase made Bitcoin more accessible to non-technical users, but in 2013 Bitcoin still faced technological problems (like an unintentional hard fork), few user-friendly interfaces, and a minimal network effects.
By 2017, Bitcoin had a proven stable protocol, a plethora of user friendly interfaces (including ATMs in most big cities and an Exchange Traded Note (ETN) that allowed Bitcoin investment via an IRA or 401k), and a user base that had reached critical mass such that Bitcoin could be purchased, traded, and spent throughout most of the world. Combining data from Coinbase with work by researchers Hileman and Rauchs (2 - Crypto Adoption Study) we estimate that the total number of bitcoin users and holders is around 45 million people today, representing about 1/2 of 1% of the global population.
Like email in 1994, Bitcoin is a robust technology ready for widespread use, but very early in its adoption curve. And like email in 1994, the small network of users means that there are few people to whom you can send Bitcoin, and this leads many to question its usefulness.
https://www.forbes.com/sites/apaul/2017/11/27/its-1994-in-cryptocurrency/#7830637cb28a