For AI companies experiencing explosive growth like Harvey (tripling ARR in a year), traditional TAM analysis is an obstacle, not a tool. Such growth signals the company is capturing a new budget pool (e.g., labor costs) that dwarfs the existing software market. In these cases, the revenue trajectory itself becomes the best indicator of the true TAM.

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The venture capital benchmark for elite growth has shifted for AI companies. The old "T2D3" (Triple, Triple, Double, Double, Double) heuristic for SaaS is no longer the gold standard. Investors now consider achieving $100M ARR in under three years as the strongest signal of exceptional product-market fit in AI.

Unlike traditional B2B markets where only ~5% of customers are buying at any time, the AI boom has pushed nearly 100% of companies to seek solutions at once. This temporary gold rush warps perception of market size, creating a risk of over-investment similar to the COVID-era software bubble.

Companies like Sierra can't justify a 100x ARR valuation by targeting the existing software market (e.g., $8B Service Cloud). The bet is that they will capture a significant portion of the much larger human labor market ($200B+ for support agents). This represents a fundamental transition of spend from human capital to software.

Comparing legal AI firm Harvey's $8B valuation on ~$100M ARR to ServiceTitan's $9B on $866M revenue reveals a market shift. Investors are underwriting AI companies not on existing market size but on the belief they will enable widespread labor displacement, creating an entirely new, massive market.

Successful AI products like Gamma and Cursor don't just add a feature; they create so much value they can charge orders of magnitude more than legacy alternatives. This massive Total Addressable Market (TAM) expansion, not a simple price bump, is the engine of their explosive growth.

The true market opportunity for AI is not merely replacing existing software but automating human labor. This reframes the total addressable market (TAM) from the ~$400 billion global software industry to the $13 trillion US-only labor market, representing a thirty-fold increase in potential value.

The narrative of "0 to $100M in a year" often reflects a startup's dependence on a larger, fast-growing customer (like an AI foundation model company) rather than intrinsic product superiority. This growth is a market anomaly, similar to COVID testing labs, and can vanish as quickly as it appeared when competition normalizes prices and demand shifts.

For venture capitalists investing in AI, the primary success indicator is massive Total Addressable Market (TAM) expansion. Traditional concerns like entry price become secondary when a company is fundamentally redefining its market size. Without this expansion, the investment is not worthwhile in the current AI landscape.

Anthropic's and OpenAI's massive revenue forecasts ($300B+ combined) aren't about displacing existing software spend. The core bet is that AI will capture a large portion of the trillion-dollar consulting and services budget, dramatically expanding the total addressable market for technology.

The traditional SaaS growth metric for top companies—reaching $1M, $3M, then $10M in annual recurring revenue—is outdated. For today's top-decile AI-native startups, the new expectation is an accelerated path of $1M, $10M, then $50M, reflecting the dramatically faster adoption cycles and larger market opportunities.