Human nature I think.
Since becoming disabled, I have come to realise people really struggle to imagine how that might feel, how it might happen, how they would cope.
If you can start to see how it could very very easily happen (some people literally wake up paralysed, some people trip over a low step and break their necks... its not all super dramatic stuff or doing incredibly stupid stuff, or being born that way)... and start to think about how you might feel... those are very unpleasant, scary thoughts. Most people do not want to think them.
Those who really can't imagine it, will just see that someone else is getting something they don't have -extra money, fancy things, shiny new car. Simple monkey greed and jealousy there.
Those who can't and really don't like the thought (the number of times I have had someone tell me with all sincerity that they'd not cope, they'd kill themselves if they were in a wheelchair like me is unreal, truly) - push it away, deny its a thing, that people exist with the needs and discomfort and struggles they have - and so if its not a thing, its not real, its not happening... then they must all be liars and cheats claiming something they're not entitled to.
And the current media phase of highlighting real or perceived benefit fraud and portraying disabled claimants as scroungers, shirkers and cheaters... plays into both mindsets very nicely.
Some of them of course will tell you that they would never want a genuine claimant to lose their support...
But of course, they believe if someone loses their support, has their claim denied they were never a genuine claimant in the first place, they were a liar and a cheat, so thats just fine, no suffering is occurring...
So when we end up with disabled people back in institutions (which will cost the taxpayer billions of course) or begging on streets - the lucky non-disabledz can fend off any guilt or icky feels by telling themselves 'its ok, its their own fault, they aren't genuine, they could just try harder, they probably brought it on themselves, what a shame but not my problem'...
Government and media, also like to point the masses one way, so they're not looking another way, and the media like click-bait of course. If they can get thousands of click-throughs to their articles by leading people to believe that benefits claimants are getting free money for having a wonky toe or being shit at maths, or are all driving around in luxury cars, at zero cost to them in any way - of course they will!!