Feeling discouraged about applying

I live with my parents
My dad(71) can still drive but he has diabetes, still looks healthy (according to my brother)but he has a retinal specialist due to diabetic retionaopathy, CAD, high blood pressure(I often check it) can do things but I usually have to sit him down when he looks light headed due to his BP.

My mom is 75 with a heart condition as well can still cook and clean but gets tired at times. I started aplicaron for both of them. But my siblings say they look fine that it not worth it if they are just going to get denied.