To quote Paul Graham: "Just as trying to think up startup ideas tends to produce bad ones, working on things that could be dismissed as "toys" often produces good ones. When something is described as a toy, that means it has everything an idea needs except being important. It's cool; users love it; it just doesn't matter. But if you're living in the future and you build something cool that users love, it may matter more than outsiders think."
To put into context, how much do you think a telco company with 26 million US customers is worth ?
If Snapchat is displacing text and calls as the medium of transient communication of the next generation, it could feasibly end up being worth a substantial amount.
(My personal opinion is that it's over-valued; but it's important that someone makes the reasoned counter-argument)