Unless you're serving Chinese open-weight models - you have to consoder training costs. If you're off my 10x, then the amortization period is 30 months - far longer than the useful lifetimes of SoTA models. Frontier model development is a Red Queens race: you have to run as fast as you can, just to maintain your position.

The discussion was if Anthropic makes money on inference. They do. They lose billions on training.

No, because Anthropic can't serve their models unless they train them.

Training is akin to the cost of building the software/product. Inference is selling the product.

It's quite easy to sell something for a profit if you ignore the costs. Ultimate free money hack. I will start selling canned beans for the price of the beans plus a few cents. I will just ignore the cost of the cans, labor, power, machines, maintenance, distribution, storage and facility space. If I do that the few cents extra are pure profit.