That’s where my thoughts have been leading, too. I remember when people used almost the same kind of condescending tone dismissing myalgic encephalomyelitis as “Incline Village yuppie syndrome” until the weight of evidence won out. I think we’re sort of primed for it with the combination of hard-to-diagnose symptoms and various cultural tropes about whingers, disability cheats, etc. — if it caused unambiguous problems (e.g. polio’s paralysis or when COVID causes lung scarring visible on X-rays) almost everyone would accept that it was real without arguing but when you have the combination of relatively low incidence and things which aren’t easy to find on a simple test, it’s just a bit too easy to dismiss. I suspect the continuing improvements in diagnostic technology are going to push out the upper bounds for how long a case of many diseases can linger.

There’s probably also some link to the reminder of our own mortality & the degree to which luck matters: a lot of people are uncomfortable with the idea of disability and want to believe they have more agency than they do.