I'm going to demand higher pay than a disabled colleague of mine
Is there a reason why you brought up the fact that he is disabled?
The company pays a higher wage to persons who have disabilities
Getting to get a higher salary than a disabled person for doing the same work is discriminatory. Accept your pay the way it is and be happy for your co-worker's making a good salary.
I just feel like I contribute more to this company. It is not just because they are disabled, it is because they barely work.
I think that everyone should get paid the same regardless of their disability status. It is wrong to think that you deserve more just because you are not disabled.