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.
Ehhhh, idk about that one, I’ve only heard it in alt-right social circles of high schoolers that I left long ago (I was never really part of the group, but they were the only people I knew). Everyone else I know would kill you if you called someone a “retard”