Venture returns follow a power law: a small number of investments generate most of the fund's returns, while the majority break even or lose money. Marc Andreessen's observation is that the best fund returns the entire fund from one investment. This shapes everything about how VCs price, allocate, and exit.
For founders, the power law is why VCs prefer 'big swing or zero' over 'reliable mid-sized outcome': a sub-billion-dollar exit is essentially the same as a zero in a fund built for fund-returner outcomes.