Barbershop vs Google

To grow fast you need two things: (a) to make something lots of people want, and (b) to be able to reach and serve all those people. Most businesses fail condition (b) structurally, not through any fault of the owner.

A barbershop makes something lots of people want. But it can only serve people within driving distance, and one shop can only cut so much hair. It isn't designed to grow fast. A search engine is: software serves anyone on earth at near-zero marginal cost, and nearly everyone searches.

Notice the constraint cuts both ways. Writing software isn't enough either. Software aimed at a niche audience, like Hungarian-language barbershop booking, scales technically but caps out on (a). A startup idea needs both a big want and a deliverable path to everyone who wants it.