There needed to be someone willing to try going big at an organization with sufficient idle compute/data just sitting there, not a surprise it first happened at Google.
Every bet makes perfect sense after you consider how promising the previous one looked, and how much cheaper the compute was getting. Imagine being tasked to train an LLM in 1995: All the architectural knowledge we have today and a state-level mandate would not have gotten all that far. Just the amount of fast memory that we put to bear wouldn't have been viable until relatively recently.
I remember back in the 90s how scientists/data analysts were saying that we'd need exaflop scale systems to tackle certain problems. I remember thinking how foreign that number was when small systems were running maybe tens of megaFLOPS. Now we have systems starting to zettaflops (FP8 so not exact comparison).
In other words, no one expected GPT-3 to suddenly start solving tasks without training as it did, but it was expected to be useful as an incremental improvement to what GPT-2 did. At the time, GPT-2 was seeing practical use, mainly in text generation from some initial words - at that point the big scare was about massive generation of fake news - and also as a model that one could fine-tune for specific tasks. It made sense to train a larger model that would do all that better. The rest is history.
It Is Difficult to Get a Man to Understand Something When His Salary Depends Upon His Not Understanding It