Armed with a better product, how can one tackle a network effect?

Armed with a better product, how can one tackle the network effect (that i think, and correct me if am wrong, is the only thing making it impossible to compete with Craigslist; At least horizontally). Every time i think about this topic, a few words bounce chaotically in my head. Don't know how they're related but: Vertical~niche, MASSIVE Chicken & Egg, etc...