Instinct, an invite-only personal AI agent, raised a $1 billion Series C from Sequoia, Benchmark and Coatue at a $10 billion valuation on September 28, up from $2.5 billion a month earlier. It has hit $1 billion in transaction volume, growing 10% a day with no marketing spend, a pace Stripe took about eighteen months to reach and Instinct reached in closer to six. CEO Noah Shin, 23, gave his first long-form interview on October 1, and Ben joined as chief business officer after nearly a decade at Snapchat. The discussion has settled on a 600 euro EU flight-delay refund as proof the agent works, while serving a personal agent costs about $1,000 per user per year. On October 28…