China can't afford to throw away only sons, and have them sink into the bottom of the ocean. Families would revolt pretty quickly. As we saw from the millions of protestors in Hong Kong in 2019, and the violent protests in Shanghai in lockdown 2023, Chinese citizens are capable of grouping together in mass numbers.

China may have the factories for manufacturing, but they need materials and money to keep a war going. That's hard when they are broke, and also supporting other dictatorships, such as Russia's war effort, Iran, North Korea.