So, you think China is building the largest military in history because of "communism". Do you recognize Chinese people as warriors? Can you remember any pro-war Chinese folklore? Communism is a relatively new flavor in their culture.
And what exactly do you think China can't reproduce in 100 years?
I'm not necessarily saying that, only that it's not an unreasonable concern given the history. Venezuela (a communist country) with Chinese ties, was going to invade Guyana before we captured Maduro. Cambodia, a country with communist remnants and Chinese ties was attacking Thailand. China has a long-standing threat to take Taiwan. It already took Tibet and helped try to take communist control of Korea.
Do you think if you were Japan, South Korea or any of those other countries, you would be sitting comfy on the belief that China has good intentions for them?
So, no, I am not _certain_ that is what China is doing with its military build up. Only that, I see it as a possibility that we can't sleep on.
Your argument about whether Chinese people are pro war isn't as relevant in a country like China as it might be in some democracy, but even in democracies war still occurs even if the population is anti-war. In China, it's just even less relevant, because they have strict social control. You could say the relevance has other angles, like more of the population has to be dedicated to enforcement and repression which takes some of that capacity away from military duties.
China can definitely reproduce a lot of technologies, but if they confirm again that they are a critical threat then there is a lot more we can do to slow their progress if necessary.