The same reason people in Russia and China didn't fight back. They didn't think it would be that bad. Most of them would go back in time and fight given the chance. American education system doesn't teach history of communism enough, so most Americans think it will not be that bad. I guess most countries must live through communism once in order for several generations of that country to understand the evils of communism. This is America's turn. Let's hope the communism here will last less time than in Russia. Let's hope less people will die because of it. Let's hope less people would have to eat others to survive like they did during Holodomor.