Sam Altman emphasizes that building a great product is the most critical thing for any startup.

He stresses that in the early days, it’s far better to have “a small number of users that love you” than many who only “kind of like it.” According to Altman, almost all great companies start this way, with products that are so good users “spontaneously tell their friends about them” or would “write the company and protest” if they disappeared.

To measure success early on, Altman advises: “You shouldn’t track absolute growth in number of users in the early days of a startup. You should just track how often they’re using it.” Retention and frequency of use are the best indicators of product love. His key point: “Nothing but a great product will save you.” Without it, nothing else—no matter how well-executed—will make the startup work.