> What motive do you see for them releasing these models for free, especially with the massive increase in cost associated with catching up?

Owning a platform. Zuck's dream.

They put tons of money into these models, nurture an ecosystem of companies built around them, and then start gradually figuring out a licensing model for the ones that take off.

Kill Op*nAI, for starter. If they see it as a threat, commoditizing the tech is a great way to get rid of them at a reasonable cost.