Marissa Mayer: Anyone who says they know how AI will play out is ‘either lying or arrogant or both’

Marissa Mayer has spent most of her career near the center of Silicon Valley, from early Google to Yahoo’s top job. At Fortune’s Most Powerful Women Summit in California, she used that history to make a blunt point: anyone claiming certainty about AI’s future is overplaying their hand.

“We have a new form of intelligence,” she said on stage with Fortune executive editorial director Diane Brady. Her view wasn’t pure cheerleading. Mayer said there is a real chance things go badly, but she put that outcome at “well less than 50%.” Even some AI doomsayers, she argued, would probably accept that framing.

That optimism rests on what she thinks AI could unlock: better medicine, better science, and more time for people to live the way they want. But she also said the industry has helped sour public opinion in the U.S. The early pitch was, in her words, “perhaps too cavalier,” and that left people worrying about jobs, families, and what AI will mean for children.

Mayer’s own path gives the remarks some extra weight. She joined Google as an early engineer, later became Yahoo CEO in 2012, and at the time was the youngest woman to lead a Fortune 500 company. She defended the scrutiny around her short maternity leave, saying Yahoo could not have a CEO gone for three or six months. After Yahoo was sold to Verizon for $4.8 billion in 2017, she started Sunshine, wound it down in 2025, and sold its assets to Dazzle AI.

Dazzle is her current bet: a personal AI assistant built around the photos on a user’s phone. Mayer said the idea came from Sunshine, where her team decided about 60% of a typical camera roll is worth sharing and the rest is the mundane stuff of life — dentist appointment cards, kids’ cleats, and all the reminders people forget. Dazzle is invite-only for now, and Mayer said users can give it full, partial, or no access to their photos, with sensitive images discarded immediately. The company plans to make money from subscriptions, transactions, or both, while keeping a free tier.