It should be noted that DeepSeek routinely claims to be a "language model trained by OpenAI", so it's pretty clear that it wasn't trained at 10x less cost from scratch, but rather on synthetic output generated by ChatGPT.

Not to point a finger at DeepSeek specifically; this is generally the case for best open source models right now. The best LLaMA finetunes tend to also use ChatGPT-generated synthetic datasets a lot.

Either way, it's unclear what the real cost is when you factor that in.