| url | https://www.impromptubook.com/ |
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Reid Hoffman’s book co-written with GPT-4 — half manifesto, half live demo of what the model could do at the time. Notable for being one of the first popular publications to put concrete numbers on ChatGPT’s adoption velocity.
The cited claim
By the start of February 2023, OpenAI said ChatGPT had one hundred million monthly active users, making it the fastest-growing consumer internet app ever.
That single sentence reframed the AI conversation. Before Impromptu, the narrative was “interesting research demo.” After, it was “fastest consumer adoption in history.” The number became the canonical reference for ChatGPT’s PMF moment.
Why it matters here
Hoffman’s book is less interesting as theory than as an artifact. It’s evidence that the people closest to OpenAI — Hoffman was on the board at the time — were themselves stunned by the adoption curve. PMF this strong is so rare that even insiders mistake it for a temporary spike at first.
See chatgpt-pmf for the full case study, product-market-fit for the underlying concept.