I think it's because it's a great rationalization, that people like because it makes them feel good. It lets people think that they are the responsible ones, and that since everyone else is a moocher who is lazy (or perhaps disabled because they offended god in some way). And so, they get to rationalize that they are the superior people, literally better than everyone else. Humans find such stuff irresistible.
It's also a good rationalization against uncertainty in life. If you can believe that are the right kind of person, then you never have to worry about random calamity befalling you and your loved ones. That's because calamity only happens to those who deserve it. Who deserves it? People who don't prepare, or work hard. Scammers.
Thus, logically, people who experience calamity didn't prepare, work hard, and aren't mooching. People who worked hard and had a calamity don't exist -- you know, because of logic.
I suspect this is why the privileged classes like such ideologies. They don't have practical experience with random devastating crap. The human ego loves to take credit for went right, whether or not it had anything do with it or not.
Overall, I think current politics is playing on selfishness. And selfishness is very very easy to appeal to. So much so that if you tell people the right lies they'll believe them without any real evidence.