Many Leftists--perhaps most of them--and even some of their leaders--are merely stupid, too stupid to comprehend the evil that results from their stupidity.
Some of these people know that they are stupid and are following the examples of those they deem more intelligent.
Some of them however do not know how stupid they are, especially those who, like idiots savants, find within themselves channels of intelligence that reassure them that they are not stupid, but who lack the wit (or the desire) to understand how limited these channels actually are.
I'm thinking of a theoretical physicist whom I saw on television and who is obviously quite intelligent in the field of theoretical physics but whose thinking outside this limited field are astonishingly stupid--and he has no comprehension of this because his intelligence in this narrow field convinces him that he is intelligent in all ways, though he is woefully not.
People like this declare themselves--in spite of themselves--constantly: in acedemia, on television, celebrities, self-appointed experts and spokespersons--everywhere.
The world is full of such un-self-aware idiots savants, and because of their lack of self-awareness they are dangerous.
I think the technical term for the people you describe is neither “stupid”, “idiot”, nor even “ignorant”. I believe the proper term is “fool”.