[FrontierPsych]

Because Taiwan is the single most important producer of semiconductors in the world, is the most important reason. If China gains that, they gain the world. Everything is dependant on that. They would have a chokehold on the world.

Also, Taiwan is an unsinkable aircraft carrier. https://en.wikipedia.org/wiki/Unsinkable_aircraft_carrier

It can be used as a staging location for an attack on China, same as Cuba could be for Russia. Look what the USA did there.

[rnk]

I see the main reason is that it's a core tenant to Xi's current CCP that there will be one China and they want to destroy them. The existence of a Chinese democracy is intolerable to them. It certainly goes against the stated vision that the communist China state will be the most powerful country in the world, lead all the Chinese people, etc. Just like Honk Kong was an intolerable example of (basically) free and democratic thinking.