I think it’s more that there’s so many idiots that it’s inevitable some of them get to rule us.
Idiocy and stupidity are related concepts. Here are two of my postings about the standard textbook on stupidity from another thread:
[1] I like my definition of stupidity. Being unaware of one's ignorance is another form of ignorance.
However, yesterday I started reading a very short book: C M Cipolla, The Basic Laws of Human Stupidity, Doubleday, 2019 (original version 1976), where the author discusses (axiomatically) the nature of stupid people, rather than stupidity itself.
Looking ahead past my present bookmark is his Third Law: "A stupid person is a person who causes losses to another person or to a group of persons while himself deriving no gain and even possibly incurring losses."
The author is describing harmful stupidity, worse than in my definition.
[2] By the way, the five basic laws of C M Cipolla, discussed in the book I mentioned, are
(1) Always and inevitably, everyone underestimates the number of stupid individuals in circulation.
(2) The probability that a certain person (will) be stupid is independent of any other characteristic of that person.
(3) A stupid person is a person who causes losses to another person or to a group of persons while himself deriving no gain and even possibly incurring losses.
(4) Non-stupid people always underestimate the damaging power of stupid individuals. In particular, non-stupid people constantly forget that at all times and places, and under any circumstances, to deal and/or associate with stupid people always turns out to be a costly mistake.
(5) A stupid person is the most dangerous type of person.
(Corollary) A stupid person is more dangerous than a bandit.
The book has a strange publication history: originally privately printed (in English) in 1976, then translated into Italian in 1988, finally published in English in 2011 by an Italian publisher, then by a British publisher in 2019. Only 81 pages. The author, a serious professor of economic history, died in 2000.