This comment could benefit from a little more research. Sure, being a successful venture investor is about being in the right place at the right time, but USV is one of the best out there. Fred Wilson has written extensively about his flops and misses (they passed repeatedly on Airbnb for example), and has also written extensively about the dynamics of investing across risky-enough ideas that there are a lot of failures in a successful portfolio. Sure, Twitter has made a lot of ridiculous decisions, but as an early-stage investment, it returned the fund.