Again, you're mixing up two issues thinking they're the same thing.
The US can't defend Taiwan from China if China really chooses to invade Taiwan. China has a population 4 times that of the US. Yes, it has a GDP that is a lot smaller per capita.
But really in terms of military spending, China is pumping loads of money into specialized equipment for attacking Taiwan. The US can't base itself anywhere close to Taiwan, South Korea and Japan are the closest places with US military bases. China has been working on defending its localized maritime area from foreign forces.
For the US to actively defend Taiwan, it's going to have to spend way more than it would ever bother spending on the military and even then China would probably still win.
The reality is all the US will do is provide funding and equipment, like it's done in the Ukraine. There they were dealing with a country 4 times larger than the Ukraine invading. China is 60 times larger.
If chips are important to the US, then the US needs to make chips for the US, rather than relying on Taiwan.
But again, the issue of how important Taiwan is to microchips and the US economy is totally different to the issue of China arming itself. The US can't stop China arming itself and building up a huge military.