Top technical talent scarcity and cost.
In Silicon Valley, you can find a dozen 600k$ engineers relatively quickly to scale up a random startup.
In Germany... the salaries these people would be making would be This disparity in the valuation of top engineers cause many to emigrate, and once you are in the US, it is impossible to financially justify taking a 5x pay cut to go back to Germany. (You can justify it "non-financially", but these other justifications would need to offset the 500k$ yearly that you are leaving behind).
So... finding top talent in Germany is hard. If you were to find them, hiring them would be 2x more expensive than in the US. Which makes a good that's very expensive, twice as expensive.
This is one of the many reasons why the startup scene in Germany is poor. Nobody wants to be the engineer that actually builds the stuff, everybody wants to be a "manager".
It turns out that many of the engineers that get to build the stuff become excellent managers once the company grows because they know it inside out.
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TL;DR: if you are a tech company that needs top engineering talent to grow a super high tech facility up, you can't find enough talent there, and the one you find is twice as expensive as somewhere else.
As others have mentioned, the price of talent is insignificant for TSMC compared to the price of their machinery, so they can afford the 2x increased costs, but the lack of talent is harder to offset.