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