Disabilities and Self-Improvement
The first is pity, believing the person is 'giving up'. This is based on the belief that being disabled is a terrible state. If you are not trying to get out of that state, you have resigned yourself to unhappiness. This is probably the most common reaction, directed at all kinds of disabled people.
The second is to think the person is lazy. This is probably for much the same reasons that poor people are stereotyped as lazy - so that instead of admitting that they need help, we can abandon them and blame them for it. It's especially common to think laziness if the disability is undiagnosed, or if it is inconsistent in its' effects, or if it tends to make things harder instead of making them impossible.
The third, which I've seen only with behavioral conditions so far, is to think the person is looking for an excuse to engage in bad behavior. I'm sure this one is true in some cases, but overapplied. A specific form I've seen a lot is the idea that autism spectrum conditions can be an excuse for someone to act like a jerk. (Never mind that jerks and autistics act totally differently, and that typical autistic behavior is only offensive if you misunderstand the reasons for it.) I've also seen people claim that ADHD is a diagnosis applied to spoiled brats instead of disciplining them. I suspect this originates partly from guilt that you've treated a person badly for disability-related traits (it's seen as acceptable to bully a weirdo, but not a disabled kid) and partly from misunderstanding the reasons behind disability-related behaviors. And partly from the few individuals who really do use a behavioral disability as an excuse.
There are a small number of disabilities (eg pedophilia) where failing to overcome the condition carries a potential for real harm to others. In those cases, I think the person does have a moral obligation to try to overcome their disability, at least as much as is necessary to prevent harm to others.
But most disabilities cause no harm to others. And most, if properly accomodated, don't even cause harm to the person who has them. Many can be dealt with just as well or better by changing the person's environment, instead of changing the person.
And many times what gets lambasted as failure to overcome a disability is in fact realistic adjustment to that disability. For example, I've heard of several people who can walk with difficulty, used to walk full-time, and now use a wheelchair or scooter to get around. Many of them, when first making the transition, were accused of 'giving up', when in fact they simply wanted to be able to get around easily.
I'm of the opinion that we should not expect any more effort from a disabled person than we would from a non-disabled person. Some people will exert tremendous effort to reach a goal they find personally important, such as Olympic athletes. Others will decide that they'd rather have a life than reach that particular goal. Why shouldn't we view overcoming disability the same way?
And the cool thing about discovering that you have a disability is learning to try differently instead of just trying harder. For example, instead of exerting your full effort to learn to read in school and still falling short, a dyslexic person could get teaching that suits their learning style and allows them to learn easily. Instead of spending an inordinate amount of effort on a basic skill, you can get accomodations so you can direct your attention to more important pursuits. Instead of fighting to force your brain into an activity it's not ready for, you can learn to follow the thermals and get much more done with less effort. These are the reasons why we indentify disabilities, and seeing the disability merely as something to be overcome interferes with this goal. (Incidentally, most self-diagnosed people self-diagnose largely for this reason too. Many disability coping strategies can be implemented even if you don't have an official diagnosis.)