I'm not saying everyone, but a good number of people are making claims because they can, not because of a real problem. My grandfater could tell some crazy stories from wwII, yet there were no disability checks being handed out then. He went on to start very successful businesses. He was happy into his 70's when he died very wealthy.
One of my good friend's is outta the Air Force on full disability and he knows there is nothing wrong with him...at least not the govt's fault. He has some problems eating fatty foods because of a problem with his panceatic duct. He will be on enzymes the rest of his life and his healthcare also paid for.