Carlo Cipolla 's "The Basic Laws Of Human Stupidity"

A l w a y s  a n d  i n e v i t a b l y  e v e r y o n e  u n d e r e s t i m a t e s  t h e    n u m b e r  o f  s t u p i d  i n d i v i d u a l s  i n  c i r c u l a t i o n .

Moreover, its not only that we are stupider than we think, we are also less competent than we think! Ha! Check the Dunning-Kruger effect and/or this pdf