The study you are referring to is known as the Dunnin-Kruger Effect. It goes a long way toward explaining Leftist thought...
Thanks for the reference.
Just for fun, you might look at the “RationalWiki” article about it. It uses Rush Limbaugh as an example of ignorance, and Al Franken as an example of knowledge and humility.
I believe you are correct about leftists. But people can be very smart and reach the wrong conclusions, when they start from false assumptions about the nature of reality.