Comment by Yizahi

LLM business is not a one-shot figure it out and then collect some easy money, it a constant work and expenses just for LLM functionality. So if Apple analyzed this and decided that they would rather rent such capability, it seems quite logical. Also Google already has ties to Apple, they may even strike a deal where search on iOS is bartered (maybe partially) for Gemini service. Win-win. And Google is not going out of business any time soon, so more reliable than any pure-LLM corporation.

Another, less likely possibility is that Apple may be reluctant to steal enough data to train own LLM to a competitive level and then continue this in perpetuity. They have this notion that they are privacy oriented FAANG company, and may want to keep up this idea.

Maybe it is a sum total of a lot of factors, which in the end tilted the decision to a rental model.