They don't. Snapchat is a feature, not a product. They should have sold to Facebook when they had the chance.

Now everything novel they had (expiring message, stories, filters) has been successfully aped by Facebook and incorporated into Instagram, and because Instagram offers a UX that isn't intentionally shitty, they've already shot past the Snap userbase.

Sell your stock now, and don't be surprised if they're irrelevant/bankrupt by 2019.