I still find this VERY hard to believe. I could be wrong (and very well might be), but Snapchat still seems far more of a Groupon type of company than a Facebook.
We'll have to see how well they can deliver/scale Discover, but I remain unsure they can ever find a way to exit and become worth this amount with the types of users they have (very young, very unloyal to services, very difficult to monetize because of youth -- look at the ridiculous Snapcash product for instance -- requires a debit card/user to be 18, when 80% of Snapchat's audience is 13-17 and thus unable to use the feature).
I just don't know.