It was sarcasm. They were saying that society sees smokers as people who are "worse thing in the world after the Third Reich," not that they actually believe that. The point they were making is that people view smokers in a bad light but hypocritically it's taboo to view the obese in a bad light.
> while smokers (or meth addicts, or gamblers, or other sorts of compulsive behavior) are almost the worst thing in the world after the Third Reich.
which is just complete BS. There are way worse things in the world happening than that - every minute! (No, I don't smoke, gamble, do drugs or alike)