The part that's surprising to me is how instantly popular of a startup it became with so little information. Was this "demo" they gave so damn good that all the investors (some really reputable ones such as Google) started throwing money at it, without doing their research to see how real it was?
Perhaps growth just isn't a great metric for future growth. For example, tons of food-delivery and pet-product startups have exponential growth early on and evaporate a bit later when the product ceases to be sold at cost and a newer competitor appears.
Sounds very suspicious to me.