1) It made no economic or military sense for the Nazis to spend so much time and energy slaughtering Jews instead of having them work for Germany in some capacity
2)It made no economic sense for Stalin to let peasants starve in the Ukraine instead of making concessions so that they provide food in the future
3) It made no economic sense for Pol Pot to send city dwellers into the Killing Fields in Cambodia instead of producing industrial goods. Hell. it doesn't make sense from even a Marxist point of view. I am no fan of the guy but at least Marx wasn't against industrialization to put it mildly.
4) It made no sense for Mao to try to wholesale replicate Stalinism in China. He did so anyway.