The static size of a Total Addressable Market (TAM) is a misleading metric for big ideas. A better evaluation framework focuses on two questions: Will the product's innovation cause the existing TAM to grow multiple times over? Can the company layer on additional, new TAMs over its lifetime?

Initial data suggested the market for design tools was too small to build a large business. Figma's founders bet on the trend that design was becoming a key business differentiator, which would force the market to expand. They focused on building for the trend, not the existing TAM.

According to Shopify's President, the key to building the next wave of billion-dollar brands isn't capturing a slice of an existing market, but creating a new one entirely. Brands like Skims and Gymshark succeeded by redefining their categories (shapewear, athletic apparel), effectively creating new TAM rather than just competing for it.

Traditional market sizing, which analyzes existing demand, is useless for true technological breakthroughs. A fundamental change on the supply side (e.g., GPUs for AI, cloud for software) unlocks markets that are orders of magnitude larger than their predecessors (e.g., gaming, on-prem software).

Analysts often mistakenly constrain a disruptor's potential to the size of the existing market it's replacing (e.g., valuing Uber based on the taxi market). Truly disruptive products create entirely new behaviors and expand the total addressable market (TAM) by orders of magnitude, a key insight for valuing high-growth companies.

Shopify's evolution shows that initial TAM estimates can be conservative. By strategically expanding into adjacent "horizons" like payments, companies can "add a zero" to their market opportunity. This justifies long-term growth and high valuations, a lesson Bessemer now applies to its portfolio.

VCs in 2008 rejected Shopify because the existing market of 40,000 online stores was too small. They failed to see that Shopify wasn't just serving a market; its friction-reducing product would create a much larger one.

Companies like Amazon (from books to cloud) and Intuitive Surgical (from one specific surgery to many) became massive winners by creating new markets, not just conquering existing ones. Investors should prioritize businesses with the innovative capacity to expand their TAM, as initial market sizes are often misleadingly small.

When evaluating revolutionary ideas, traditional Total Addressable Market (TAM) analysis is useless. VCs should instead bet on founders with a "world-bending vision" capable of inducing a new market, not just capturing an existing one. Have the humility to admit you can't predict market size and instead back the visionary founder.