I recently listened to the NPR "How I Built This" episode with Lonely Planet founders Maureen and Tony Wheeler.
They started Lonely Planet in 1972. They had just finished a long and adventurous road-trip through Europe and Asia (the so called Hippie Trail). After the trip, they were constantly asked for recommendations from friends, so they decided to encapsulate their learnings in a book if only to alleviate the need to retell the same stories. They wrote and self-published a small 94 page booklet called "Across Asia on the Cheap". This book sold well, and encouraged them to take the project seriously and continue on.
Maureen and Tony emphasize in the podcast that their success did not come overnight. They grew their following with each new book and eventually built a sustainable business.
They likened the experience to pushing a snowball down a hill, where you have to push a lot at first, but which then begins to pick up momentum and increasingly grow on its own.
This analogy works for many startups, especially those relying on content, community, or data as their primary levers. It's something I'll keep in mind.