a16z's investment philosophy is to assess founders on how world-class they are at their core strengths. Horowitz warns it's a mistake to pass on a uniquely talented founder due to fixable weaknesses (e.g., no go-to-market plan) and an equal mistake to back a less talented founder just because they lack obvious flaws.

A VC anecdote reveals a critical flaw in founder selection: optimizing for "coachability" can filter out the sharp, difficult "diamond" personalities who often generate the greatest returns. True alpha comes from backing the brilliant and uncoachable, not the merely compliant.

To effectively spot founders with an extreme, outlier strength, an investor needs to have a similar "spiky" profile. The ability to recognize genuine, world-class expertise comes from having achieved it yourself in a domain—a "game recognizes game" phenomenon.

Brian Singerman's venture strategy was almost entirely focused on founder assessment, making up over 98% of his decision. He famously doesn't read financial reports or use spreadsheets, instead concentrating all his effort on one question: is this founder the best in the world at something novel?

Rabois's investment formula requires a founder to be the absolute best he's ever met in at least one specific dimension—be it intelligence, tenacity, or strategy. He avoids investing in founders who are merely B+ across the board, betting instead on extreme, world-class exceptionalism.

While assessed during diligence, the true caliber of a founder—their passion, authenticity, and ability to "run through walls"—becomes starkly clear after the deal closes. This distinction is not subtle; the impact of a truly exceptional founder versus an average one is immediately evident in the business's trajectory.

The Founders Fund concentration model is widely copied, but its success hinges on a difficult truth: most funds won't contain a SpaceX. The critical skill is the discipline to *not* force a massive bet on your "best" company if it isn't truly generational.

Horowitz instructs his team to focus on how exceptionally good a founder is at their core competency. He warns against two common errors: passing on a world-class individual due to fixable weaknesses, and investing in a founder with no glaring flaws but no world-class strengths.

The quality of the founder is the single most important variable. A great founder with a mediocre plan will outperform a mediocre founder with a great plan. The best investment strategy is to back exceptional people and give them leeway, as they will create upside that breaks all precedents.