Fireworks, Baseten, and Together AI collectively raised $3.8 billion in four weeks, all betting that the real money in AI isn't in building the smartest model — it's in running someone else's cheap one. Fireworks closed a $1.5 billion Series D at a $17.5 billion valuation on July 15, joining Baseten ($1.5B at $13B) and Together AI ($800M at $8.3B) in a sprint to own the inference layer. These companies don't make frontier models. They sell the plumbing: batching, quantization,...