Costs also have to include the amortized training costs.
But the API price is likely simply regular supply and demand, charging as much as the market will pay. Corporations are dropping insane amounts because it's still peanuts for many industries. Software has just been ridiculously cheap before AI. So high prices are still low for companies if it eases some bottlenecks.
The costs only have to include amortized training costs if you are trying to be profitable overall. Having positive unit economics and VC subsidized fixed costs is pretty standard.
What happens when the VCs decide to stop dumping more money onto the fire?