Apple has built the strongest ecosystem of AI-capable consumer products in the industry. I suspect they deliberately chose not to compete in the AI data center race. Entering that arena would have cannibalized sales of their own high-margin devices, while further straining their already tight supply chain for memory and M-series processors.
Apple would never willingly pay Nvidia for GPUs anyway.
Why absorb supply chain pricing pressures and volatility when you can pass those costs directly to the consumer?