1. Google pretty much invented the technology (https://arxiv.org/abs/1706.03762)
2. In order to create the models one needs lots of compute and access to a lot of text. Google scores higher than OpenAI on both counts.
3. New models are released on a weekly basis by all sorts of companies. So OpenAI has no monopoly on LLM models. In fact their competition is staggering (NVIDIA, Meta, Google, DataBricks, Amazon (numerous other startups)) It will not be long before there are even more.
It seems to me that Altman saw this all as a timing thing. Reveal your cards now and force others to do the same in the hopes of obtaining a strategic position over competitors. Googles cashflow seems to be doing just fine and I haven't had to fight off any urges to use Bing.