Start a marketplace by subtraction, shrinking to one obsessive niche dense enough to reach liquidity, then re-broaden one ignitable niche at a time as the flywheel compounds.
Whatnot
Whatnot is a livestream shopping marketplace where sellers run live video auctions and buyers watch, chat, and bid in real time. It began as a "sell anything" platform that failed to ignite, and its story is a single lesson told twice: you start a marketplace by subtraction, shrinking to one obsessive niche dense enough to reach liquidity, then let the resulting flywheel compound as you re-broaden one ignitable niche at a time.
Cold Start: shrinking from "sell anything" to Funko Pops
The problem. Founded in December 2019 by Grant LaFontaine and Logan Head, Whatnot launched as a broad marketplace to buy and sell anything, essentially a "high-end Craigslist." It failed to ignite: spreading supply and demand across every category meant weak signal, no community, and no liquidity in any single niche, the classic cold-start failure of a horizontal marketplace with no dense atomic network inside it.
The approach. Whatnot retreated to a single, almost reckless-looking wedge, Funko Pop collectibles, a dense, high-frequency community with shared vocabulary and known grail items. It paired that focus with a new format, adding livestreaming in summer 2020 after Head spent about six weeks coding it following YC's W20 batch, and LaFontaine personally ran the first shows to seed the supply side directly.
How it solved it. Concentrating all supply and demand into one niche let a single show reach liquidity, enough buyers to make an auction lively and enough sellers to fill a schedule. Whatnot's first livestream on the app sold roughly $5,000 of Funko Pops in a few hours, which both proved the live-auction format converted and showed other collectors they could earn real money selling live, pulling in the next wave of sellers.
Network Effect: re-seeding the flywheel category by category
The problem. One ignited niche is not a business. Whatnot needed the Funko flywheel to compound and, harder still, needed a repeatable way to broaden into trading cards, sneakers, comics, and beyond without re-diluting the liquidity that focus had won it.
The approach. Within each niche, more sellers running shows gave collectors more reasons to keep the app open, which put more buyers in each stream, which lifted seller earnings, which drew more sellers: a self-reinforcing loop. Rather than going horizontal all at once, Whatnot re-ran its Funko playbook one vertical at a time, finding the obsessive community, seeding a few credible live sellers, reaching liquidity, then repeating, so each new category launched as its own fresh atomic network.
How it solved it. The compounding loop scaled far past collectibles: sellers moved $3 billion of goods through live sales in 2024, and Whatnot projected roughly $6 billion in merchant sales for 2025. In October 2025 a $225 million Series F co-led by DST Global and CapitalG valued the company at about $11.5 billion, more than double its valuation earlier that year.