"liquidity quality matters more than liquidity breadth"
"marketplaces built around monogamy e.g. doctors, haircutters, babysitters much harder to scale than marketplaces built around promiscuity e.g. restaurants"
"Fragmented supply, high frequency, SMB suppliers, young businesses are characteristics of wildly successful investments"
Travel pretty clearly qualifies for supplier acquisition driven outsourced marketing yet BKNG + EXPE = $100B mkt cap