One of the many incentives to protect Taiwan.

Many nations want China to stay within the first island chain. They're aggressive in term of territory claims.

The current hegemony of USA is more palatable and predictable for them than China's.

To be fair, Taiwan would want USA to be stronger and also the majority of their customers are USA companies.

It's a gimmick not the real size. Anything 5nm and beyond is now just a marketing term for the technology generation like 2.0 and stuff.

They started to stack transistors (3d) and stuff now so they can fit more. It's not like they shrunk it even further yet.