I can sortakinda understand why people do it. 'There but for the grace of God go I' is a very scary thought. It highlights exactly how little control you have over your situation. But when you then apply it to 'I can do X because I'm so special and cool with self-discipline and making all the right choices, why can't that bum on the street have discipline too? Clearly he is unworthy' it becomes obnoxious.