What does this equation mean?

None of these three accounts contradicts the others; they describe different positions in the same equation from different vantage points, and the disagreement worth naming is about which term each party has the strongest incentive to foreground. A chip vendor foregrounds $c_{d}$ against $c_{\mathrm{cloud}}$ . A model vendor selling API access to multiple sizes foregrounds the existence of a genuine quality-cost curve rather than a single right answer. A platform vendor foregrounds who pays $C_{\mathrm{dev}}$ and U rather than whether they are paid at all. DeepSeek’s own disclosure practice is a useful corrective to take from all three: a company reporting a training cost explicitly flagged as excluding “prior research and ablation experiments” [ 5 ] is, in effect, warning its own readers that a headline dollar figure — theirs included — is very rarely the full engineering bill. That warning applies with at least as much force to marginal-cost claims about on-device inference as it does to training-cost claims about frontier pretraining.