They met at 10 p.m. each weeknight, after class at Columbia University. Sometimes talking over Zoom until 2 AM, Anish Agarwal, Raaz Dwivedi, Ahmed Lone, and Raj Agrawal talked about what it might mean to walk away from their lives—for a startup. All academics in some form or fashion, the group swapped ideas at the intersection of their research: causal machine learning, reinforcement learning, and AI agents. For Agarwal, the decision wasn’t to be taken lightly. That semester, he’d just started a...