Did he actually believe in communism? Or did he just see an opportunity to be dictator and took it? There was plenty of industrialization that needed to happen prewar and plenty of rebuilding after the war, so it’s actually hard for me to see his true ideology.
What do you mean by communist? Karl Marx died ages before the Russian revolution, he knew nothing about it. According to Lyndon Orr, who wrote an early piece on him, he was not a cold rational man, but rather a dirt poor and very passionate man, who adored his own wife. When he wrote about poverty he wrote about the poverty of characters like Little Dorrit, the world of undeserving poor, child labor and so on. There were many reasons for the Victorian poor to be angry. The Russian revolution occurred in 1917, and stalin died in the early 1950s. If you by communist mean that stalin followed lenin, you might be right. You might also be right in assuming that Marx himself was an advocate of violence to achieve ends. But it came from a place of hurt, and it was by no means any genocidal rage or psychopathic coldness about him. There is a very odd story about Vienna, at one point in 1913 both stalin and hitler were in the same parts of vienna, but as far as we know they never met.