Also, recommending a black box managed solution isn't an option for some large companies that have their own hardware & datacenters and which may want to use open source solutions they can easily deploy, fork and support themselves to keep costs under control.
They should be using the best technical and cheapest solution, and they owe it to their investors. At their scale they will never be able to use anything else than a cloud solution.
They could solve these issues at the number of users they report, for a monthly bill below 25 million dollars.
"6,311 database instances running the PostgreSQL-compatible and MySQL-compatible editions of Amazon Aurora processed more than 376 billion transactions, stored 2,978 terabytes of data, and transferred 913 terabytes of data" - https://aws.amazon.com/blogs/aws/how-aws-powered-prime-day-2...
That's definitely not true, and there are many companies doing higher volumes at a fraction of the cost-per-query.
Although scale doesn't force companies into public-cloud database systems, considerations like capital, time-to-market, and business strategy often do. In this case, OpenAI is trading a significantly higher per-query cost for benefits like improved agility, turnkey compliance, etc.