The difference there is that Bitcoin was the first cryptocurrency and still took a couple of years before it could claim "viral" growth.

Facebook was the second mass-adopted social platform after Myspace which had millions of users. Facebook made the UI better and therefore it did not take long for those millions of users to switch to the new platform.

The difference now is, there are several mass-adopted social platforms, all fighting for attention. The new ones that gain attention, are the ones that use the "big 3" of Facebook, Twitter and Instagram to the best of their advantage.

On top of that there is in-app advertising which was not around in the days of Facebook or Bitcoin. If it was, there can be little doubt that Facebook would have utilised the medium to spread its message.

Cg