This seems very pertinent in today’s political atmosphere!
As it says it's not that people are stupid but circumstances can encourage stupidity. When people feel their lives are worthless and the world is crashing they become paranoid and desperate and often look to others to blames. Absolutely, it is created and driven by sociological situations. When we go to blame others perhaps we should try to look at the conditions that created a situation.
It was not lost on me that the cartoon character of stupid is orange. This and the Friday info drop of facebook knowing their algorithm fed into this is maddening.
The main cause of stupidity is not lack of brain power, most of us can manage, for example, long division, if given enough time and tutoring, but that is the problem, time, effort and duty are required.
The main causes of stupidity are laziness, impatience and selfishness, and of course the fact that where there are such human weaknesses, then like all human weaknesses, there are alway thousands of clever and morally bankrupt people, willing to exploit them for profit and power, by feeding those weaknesses.