system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why did Joseph Stalin kill so many people?
gpt
He had a vision for Russia and the world, and thought that fulfilling it was more important than lives of millions.

Russia, renamed the USSR, was the world's first self-proclaimed socialist state. Stalin reasoned that sooner or later she would have to fight a war with the capitalist states. In order for her to win, she needs tanks and guns, which have to be built in factories. The technologies and machine tools for them will have to be bought from the West. The only thing Russia could export in return was grain. The problem was that during the Great Depression, the price of grain on the world market dropped. So Russia had to export more, and the Russians themselves got to eat less. In 1932-33 around 7 million Soviet citizens died of hunger. Stalin thought that this was a worthy price to pay for the Soviet Union to export enough grain to import enough machine tools to build enough tanks to defend herself in a future war with capitalist states.

In June 1941 the Soviet Union had 14000 tanks against Germany's 4000. This did not do the Soviets any good; most of the tanks were abandoned and the Red Army almost crumbled away. A popular modern Russian author thinks that this was because ordinary Red Army soldiers did not wish to fight for the regime that starved and killed its citizens by the million in pursuit of Stalin's vision.