We have decided some brain quirks are disorders (and get accommodations, as is compassionate), whilst others are flaws (and get slurs). But no one picks their hardware. You cannot earn a better prefrontal cortex or deserve a calmer amygdala. Nor does one get to pick the environment they are born in, which will inform their choices later in life. Even the capacity to “learn better” is a roll of the dice, some brains start the race with sprinting shoes, others with lead weights.
So when we call someone stupid, lazy or insane we are not describing a choice, but simply announcing which kinds of unlucky we’ve decided are worthy of scorn.
I think in most cases people are using stupid to describe the action or thing a person is doing and not the person themselves, people are doing stupid stuff all the time, it’s both bad and good of course, because often times the stupid things can be delightful as well. I guess it’s just a part of being human but it’s so very frustrating that we rely on some of those people to vote when they have chose to not take life seriously or think about the consequences for other people.