> and Apple would still buy from you rather than let someone else take the crown of fastest smartphone...
... and invest in making their own chips from end to end in a couple of years. Apple has proven that they do not hesitate to completely take over stuff with the recent Intel-ARM switch when the quality or price does not match what they perceive to be fair.
TSMC is in an extremely powerful but also very precarious position - they are worth ~400B $ in market cap, and Apple has ~200B $ in cash reserves and a market cap of 2T $. If Apple wants they can either buy up TSMC whole or they can set up a competitor.