@macrobius Stupidity is not a choice it's a lack on intelligence. If the lack of intelligence is severe enough, it is a mental disability.

Well, technically the term used should probably be "ignorant" rather than stupid. Defined by Merriam-Webster as: "a: destitute of knowledge or education; lacking knowledge or comprehension of the thing specified b: resulting from or showing lack of knowledge or intelligence" the term ignorant would seem to describe the woefully common condition of the population. This definition leaves plenty of room to include "willful" ignorance.
However, turning again to M-W, where the term "stupid" is defined as: "a: slow of mind; obtuse b: given to unintelligent decisions or acts; acting in an unintelligent or careless manner c: lacking intelligence or reason; brutish" does allow the term to include unintelligence not explained by physiological deficits.
There are plenty of people out there who have no innate (or trauma induced) lack of normal brain function yet they act in ways that can best be described as STUPID. To me, it seems that in recent years it has become, for some portion of the population, "cute" to be stupid or ignorant, or to appear that way. That is the only way I can wrap my mind around the number of people who, at a time when pretty much all knowledge is available at their fingertips, lack so much basic information, have little talent for critical thinking or reasoning and worst of all, show no interest or need to improve their condition.
Perhaps, in the future "stupidity" or more likely "willful ignorance" will qualify as a mental illness. If being/acting ignorant (stupid) becomes faddish and is taken up by significant numbers of people who are capable of normal cognitive functioning, this "diagnosis" could find it's way into the DSM. After all, if nicotine dependence made it, why not willful ignorance?

I have worked with people who have intellectual disabilities my whole life, my sister is one who has suffered from birth. A stupid person is one who is capable of doing better but doesn't, people with intellectual disabilities try at least as hard as the rest of us to be their best.com/

@Rugglesby What about those people eating Tide pods?

@Sarahroo29 You got me, I have to ask. I have seen a few mentions on this site of Tide Pods. What are they?? I have never heard the term.

@Rugglesby You wash your laundry with them. It's detergent. Tide is the brand.

@Sarahroo29, phew, thank you. It is not as bad as what I imagined. I was thinking along the line of raw sewerage left on the beach at low tide.

@Rugglesby I made a post about the Tide pods yesterday.