Most people will have conflicting emotions on the subject if they think about it. On the one hand we have China, a wickedly authoritarian government that wants to conquer a relatively free, democratic neighbor. If the Chinese government gets Taiwan, it will be terrible, and you'll watch a parade of victims be murdered and punished on TV for years. There's no sugar coating this--watching the unopposed conquest of Taiwan will blow your mind and boil your blood, and you can't even imagine what the event will be like until it actually unfolds before your eyes. We made promises to those people.

On the other hand we have America and its allies. They are increasingly authoritarian and bent on world conquest. Leadership is wicked, perhaps not as bad as the Chinese leadership, but bad. Moreover, America is much more aggressive than China. It would be a very good thing if the empire and the perpetual war machine came to a halt. If America stands by and lets Taiwan fall, the empire will never recover from it. Nobody will ever believe their promises again, not for generations. This might ultimately be a good thing, but it sure won't feel good while it happens.

Finally, there is the war itself to consider, and the simple, practical question of whether it can be won. Nobody can know. It could be very bloody, or it could be short, sharp, and decisive. You can't discount the presence of Japan and its mighty navy and the possibility of other nations joining the war, too. China does not have to be invaded and conquered, it just has to be prevented from crossing the strait. We do know that it would be a terrible risk for all involved, and the cost could be very bitter indeed.