My guess is they wanted to snatch all their existing customers? Not familiar with the app. It seems to me ChatGPT wants to replace Cora and Siri. The Jarvis of AI.
This really got me curious. I watched the demo and was unimpressed. I mean, this is what Apple Intelligence is for but I never enabled it (and Apple is not pushing it too hard up our throats). So I wonder what's Altman plan on this, really. Do they really plan to market this product to Mac users or is something else at play? (Not that it matters much, with the amount of money he has he can experiment freely and buy whatever he wants.)
This probably played a role (cash out before bubble pops) plus the acquihire. OpenAI is building a try-everything-and-see-what-sticks product company on top of the model research lab so strong product teams are very useful to them.