Facebook grew so fast in the beginning because it allowed friends to connect to friends in an instant and find friends by using thier name and photo etc. this was obviously groundbreaking.
Currently Steemit does not offer this facility.
The Driving factor here is the potential to earn money from posting, upvoting curating etc.
It all depends on what the masses think of it when they come to steemit, once they manage to create an account that is eh hum!!
The crowd is a strange and unpredictable creature, so it is hard to tell what they will do.
I am hopeful though, I believe Steemit has the potential to improve Facebookers' intelligence drastically! :)
RE: How Steemit can get the next FACEBOOK bump!