So it makes sense to me that Google, which derives most of its revenue from search, would find the advent of LLMs to be existential to its core business. 

But why do you think Meta is investing as much in AI, given that social networks are pretty sticky and wouldn't necessarily be impacted from a business model standpoint?

My guess is that all the mega tech companies have a lot to lose (not just Google) to see OpenAI lock the industry-leading LLM behind an API. You see partnerships that tell this story between Microsoft partnering with OpenAI and Amazon with Claude