It's the fact that up until now, we still have no concrete evidence of who the creator is/are.
See? Until now, I still don't know what I will use to address Satoshi. Is it he? She? They? Them? Is? Are? Talking about pronouns, eh?

Kidding aside, this is the one that surprises me the most especially in an era where validation is pretty much becoming a norm, and popularity is becoming one of the ways for a company or whatever they have to market themselves. Satoshi remained anonymous the whole time, and Satoshi let the community spread the word of Bitcoin. With lots of information that we could get online, we still can't get concrete evidence on who Satoshi is/are, and the only thing that we can do is to speculate who really Satoshi is/are. Many documentaries have been done, people speculating who Satoshi really is/are, and a person who claims that he's Satoshi. If you know what I mean.

Survivability? As long as there's a huge community around it, it will survive. The creator being anonymous is what surprises me the most.