I'm suggesting that they know a few facts.
1. A lot of compute is needed now for training.
2. Training will keep happening even as tech changes.
3. Lots of people will want access to advanced AI, i.e the models too big to run an inference on a phone or laptop. i.e the ones that will be the basis for various SAAS.
4. Compute will be the currency of the future. $10 billion now is a lot, but the cost as time goes on may rise, so just get in there and get it built.
5. They are hoping for a change in the deal with Open AI so that when AGI hits, they'll be in a 49% position to use it. (Assuming Q* isn't already AGI)
6. They want to be a dominant company and are prepared to take the risk given they still feel a smack on the bum from missing out on the whole mobile phone market.