OpenAI started out with the intention of being a non-profit, but realized over time that it made it difficult to compete in terms of salary and hardware, so pivoted to a 'capped' for-profit.
As for Microsoft, my guess is their investment was just another investment in a hot AI 'startup'. It was sheer luck, and being in the right place at the right time, that they hit a gold mine with that investment as ChatGPT took off, but otherwise this would have been just one of their many investments that disappeared into the ether.
The most surprising thing to me is how hard and fast Microsoft pivoted once they realized they had a golden goose on their hands, with the Bing / Edge and other integrations they are doing. Never though I would see them move that fast, kudos.