China has been using US money to research and build stealth subs, anti-satellite weapons, and who knows what else. I'm not sure the US would win a war over Taiwan. More likely we would have a 50 year agreement like the UK made for Hong Kong.
Taiwan has the world's 20th largest economy, bigger than Turkey, Austria, Indonesia, Saudi Arabia, Norway, Poland, South Afria, just to name a few. It is also a democratic country. For us to negotiate away its sovereignty and place it under a Communist dictatorship would be morally reprehensible and an act of enormous betrayal.