Why do people discriminate against minority groups?
Now there's a one!
I tend to think it's a lot to do with power, those who have it, those who don't and those who are made powerless by one group who look to to take it out on another. In "The Spirit Level" (Wilkinson and Pickett), which deals with inequality within societies, they call this 'The Bicycle Effect', describing how people will often bow and scrape to their masters, then kick out at the people down below them to compensate for their humiliation. An example would be how, after the 2008 crash, many resented the bankers, but saved their real hatred for the unemployed, sick and disabled, who were labeled as causing the crash with their expensive freeloading (an attitude helped not insignificantly by BPS beliefs).
The disabled are always a easy target for this; they're 'different' in some way, and difference is always punished by those lacking in empathy, and weak-minded enough to not think too closely about their beliefs; plus they get attention that other people don't (care, help, benefits) which that lack of empathy can convert into special privileges, choosing to see what they would like for themselves (someone to do nice things for them) and omitting that which they wouldn't like (having to wee in a bucket, not to leave the house, having no legs, etc). Perhaps there is a degree of denial involved, punishing the weak to ward off the idea that, one day, that could be them - the general cruelty and neglect directed towards the elderly comes to mind
ME occupies a special place in public discourse, thrice cursed as it is.
1. We are 'different'
2. We have an invisible disability. This is tagged by doctors as a "mental health problem" so we can both be classed by some as as 'nutters', accentuating the superiority of those clearly immensely stable and balanced people, and, in a simultaneous act of double-think, having nothing 'really' wrong with us anyway, so we shouldn't require any special treatment.
3. We refuse to accept our diagnosis, which also means we are
i) refusing to comply with authority, which always breeds bafflement and resentment amongst the weak-minded (see above)
ii) refusing to engage with our illness, which means we are dragging out our privileges for all they're worth. Again, the dubious nature of these privileges is not investigated too closely - one wouldn't want to get too close to empathy as it would defeat the point, which is to find someone to take their own boring, shit lives out on.
One might say, of course, that I was trying to evince a kind of intellectual superiority for myself to compensate for my weakness in the face of these people who threaten my 'privileges'. Ho hum.