Key word here is retention. The author was in a pretty good position to be in, where the paid users were happy enough not to churn and move to the competition.

Key word here is retention. The author was in a pretty good position to be in, where the paid users were happy enough not to churn and move to the competition. Once you're there - you have product market fit, and you should presumably move into growth mode. That means more expenses on sales and marketing, and diverting r&d resources to scale (if needed) and building features that will reduce churn or help marketing. Another way to describe the situation here is - moving to growth mode too late, when you already have a good enough product to attack with but you're also almost out of runway.