Culturally their are similar, speak the same language. Mainland is Taiwan's biggest trading partner. & before the Japs was Chinese territory. and China has an iron will to bring Taiwan into the fold. What would the US gain again from making Taiwan it's territory - war and more debt.
Chip fabs can easily be built in the US on a 3 year timeline. Whereas that same 3 year timeline, maybe the PRC would've taken Taiwan.