Are you suggesting that if trade with the US stops due to a US-China dispute or war there is literally nobody else in the entire world to trade with?

China could discourage export of components and tools while encouraging export of consumer products. The profit margins are better that way, too.

You are making a common mistake of assuming rational behavior of a nation when it is controlled by consolidated power of one person. Their agenda may be driven by grandeur, or miscalculated attempt to eschew local optimum for global, or personal phobias and aspirations.

Triggers for war can become complex, and individual blame may be hard to find.

Prior to the First World War there was a view that economical interests would prevent war as well. http://blogs.reuters.com/anatole-kaletsky/2014/06/27/world-w...

Selling goods does not rely solely on competitive prices. It may also reflect the lack of alternative vendors, or the negative repercussions of defying political pressure -- as eastern European countries who rely on Russia for gas and oil to heat their houses have discovered, and near neighbors to China whos's fishing vessels now routinely cross into their waters have discovered.

Often the ability to sell is motivated by more than just economics.