well, there's a difference between people who are willfully stupid and want to stay that way such as the case you pointed out, and then there are those who have always been that way naturally. One chooses to be like that and the other does not..
I do not want to slander those born with a mental handicap as they cannot help that and I am thankful nor my daughters were born like that.
The little boy across the street from us was born mentally handicapped and he was just the nicest child. My girls played with him all the time in our yard and swing sets..
He was not anything like a certain nasty person you had mentioned..