The guy who taught ChatGPT how to talk just raised $870 million to build AI that never speaks. Three weeks. That's how long his company has existed in public. Diogo Almeida spent four years at OpenAI. He co-created RLHF, the training method that turned a raw model into something that sounds like a person. Then he left, and on September 15 he came out of stealth with a $40M seed at a $200M valuation. On Thursday a16z priced his Series A at $7.5 billion. Same company, 24 days apart, at 37x the…