Short answer: we believe in our socialist utopia on Earth, because we think it is wonderful and good intentions make horrible consequences irrelevant. Just give us total power to remake society and the world ...
Dangers of Totalitarian Utopian Visions
https://www.youtube.com/watch?v=Isp4ssqJQ_g
It’s always good for the socialists who are in power over those that are not. They also get rich for it.