it's not really investing though. Amazon will provide 50B worth of compute and Nvidia will provide 30B worth of chips etc. Google doesnt need any of those.

The only one that is really investing is SoftBank who is pushing for a faster IPO so they hope to make a profit on that and again Google does not offer that opportunity

I imagine they get a bigger slice of the pie with OpenAI than they do with Google, an extremely mature company who’s had investors buying in for 30 years.

Alphabet’s market cap is $3.5 trillion, compared to OpenAI’s $850 billion reported here.

Google has little need for more money, so the price will be much higher. OpenAI being a separate entity also means Google's competitors (Microsoft, Amazon) can invest there without looking silly.