Funnels Leak. Loops Compound.

Two note-taking apps each acquire 1,000 new users a month from ads. Identical budgets, identical products — with one difference.

App A's users take notes privately. App B's users share notes as public links, and every shared note carries a small "Made with B" footer that some readers click and sign up from.

A year later, App A still adds ~1,000 users a month. App B adds ~1,600 and the number keeps climbing — on the same ad budget.