I think they mean that the DeepSeek API charges are less than it would cost for the electricity to run a local model.

Local model enthusiasts often assume that running locally is more energy efficient than running in a data center, but fail to take the economies of scale into account.

It means that the electricity you would have to pay if you did the computations yourself would be more expensive than paying them to do it. Part of thst has to do with the fact that China has cheap electricity, also due to their massive push into renewables. Part of that is just economies of scale. A big server farm can run more efficiently than your PC on average.

China has cheap electricity.