You are right , none of the human experiments or eugenics were done by regimes that did not have ulterior motives . however as thought experiment let us say if

You are right , none of the human experiments or eugenics were done by regimes that did not have ulterior motives . however as thought experiment let us say if you can develop a safe vaccine by killing hundred people and save millions , should you do it ? Should I develop a self driving AI to choose life of child over dozen people Adults ? These are not easy questions to answer while the first may not happen , the second scenario is not far off