AMD relies on geopolitically dicey Taiwanese fabs. Why is nobody else worried about this? Berkshire divested all TSMC investments a few years ago so at least they're worried.

Those same "geopolitically dicey Taiwanese fabs" are used by almost every major chip company in the world, including Intel which uses TSMC to manufacture its Panther Lake graphics tile and all the tiles in Arrow Lake except the base tile. Nvidia, Apple and Qualcomm are just as dependent on Taiwanese fabs as AMD.

TSMC dominates world wide with 80% of the general chip market and nearly 100% in some specific markets.

Due to Trump policies (and geopolitical realities), they are building or helping to build fabs in the US and elsewhere. It's takes years to build a fab.