The average person on the street tends to think they're probably pretty smart - especially in the age of the internet. If we were to really examine their depth of knowledge on a given topic compared to an actual expert/master in the field, however, it quickly becomes clear just how far out of their depth the layman really is. Hell, most of the time they're not even on the same playing field!
Sadly, stupid people also tend to think they're actually very smart, while actually smart people often think they aren't because they recognize their own failings. This is called the Dunning-Kruger Effect
, and it explains a LOT about the world we live in.