I would guess that Apple always had plans to switch to their own arm cpus. Perhaps what happened is that their experience with Intel was so bad that they chose

I would guess that Apple always had plans to switch to their own arm cpus. Perhaps what happened is that their experience with Intel was so bad that they chose to accelerate those plans, rather than have to deal with AMD. Most likely Apple has a contract with Intel for some kind of deal on the price, so switching to AMD would incur a round of lawyers and negotiations to get a similar price. That doesn't come for free, so if they had other plans in the works, it would make sense to move faster rather than try and do something for a short period of time.