Apple chose TSMC over Intel for custom chip manufacturing in 2011 after Tim Cook criticized Intel's foundry capabilities. TSMC's responsive customer service and manufacturing strengths outweighed Intel's existing relationship with Apple for Mac processors. TSMC became the exclusive supplier for Apple's silicon, while Intel's foundry struggled, recently revamping its strategy to attract external clients.
https://www.macrumors.com/2025/01/30/tsmc-reveals-why-apple-snubbed-intel-chips/