Compare Bitcoin to any other successfull sites since the year 200. I could name Facebook, Myspace, Twitter, Spotify, the list goes on etc etc and want to know what all those sites have in common? They became successfull within a very short time and Mainstream.
Bad analogy.
Bitcoin is not a "site" and is more accurately compared to a protocol like SMTP (or its predecessors in electronic mail) which took THIRTY YEARS to begin to become mainstream.
The two main reasons it took email so long were:
1. It exists to replace and augment an extremely entrenched and historical system: mostly government postal systems.
2. The technology was not yet fully evolved into a propagated technological platform for mass acceptance.
THIS is exactly like bitcoin 2011 or so. We are in the early 90s of email and the internet when people are still asking each other about whether they have tried it or not. Today you carry a device in your pocket that delivers it, and its little relative SMS, etc. Bitcoins acceptance curve will be much much faster than emails because in part OF email and the cellphone.