I think it's a bit of both. My uncle is an engineer for a govt contractor & he's the kind of guy who thinks he's smarter than everyone, which allows him to justify lying to people that he thinks won't understand what he has decided needs to be done. He explained to me recently that the way to get ahead is to assess problems & make vague reports that allow people to read whatever they already wanted to see into the report. My uncle isn't a leftwing authoritarian globalist, but I suspect that the way he goes about things is not all that different.
I think that's how a lot of "smart" people operate & ultimately conspire. They know others won't go for reducing the world population, but that doesn't change their minds or make them question anything, it just makes them lie to forward their agenda instead. Their conclusions & the resulting aims are stupid & the means by which they'll go about achieving those aims are consciously malevolent. And then there are also just lots of NPCs who will do whatever they're told.