"The advice to focus on nothing but growth applies to startups where market risk is the dominant risk." Yep. But there's also a class of startup that we might

"The advice to focus on nothing but growth applies to startups where market risk is the dominant risk." Yep. But there's also a class of startup that we might call the Secret Hoverboard: it's the sort of problem that looks like a Twitter ("would people want to get more stuff delivered if it only costs $5?"), and when you poke at it with the stick of "doing things that don't scale", you see strong consumer demand -- market validation! Secretly, however, there's a hoverboard-sized technical problem between manual labor and profitability (e.g. "if we can just get our fleet of bicycle messengers operating with X% efficiency we can deliver anything by bicycle for a flat $5 surcharge, which will undercut the business models of all existing delivery services!") These are tricky, because people are so used to market risk being the dominant factor that they can be fooled into believing that the strong consumer demand means that the rest is easy. But really, it's telling you that people love to get something for nothing, and the market got the solution right the first time.