Why do handicapped people think they could always do everything a regular person could do?

Can't they just accept the fact that some things are impossible!! First the special olympics is obviously a joke, second i keep hearing about all these blind people and stuff climbing mount everest, and all these handicapped people that keep trying to accomplish ridiculaous tasks that nobody really cares about! It like "oh cool your bling and you could skydive well whoopdeedoo! You could still do it better if you wern't handicapped or in a wheelchair." What are they trying to prove?