I feel like the vitriol also in large part comes from this. A lot of people know that it is unethical and wrong but in order to acknowledge that they would either have to change their behaviour radically or acknowledge that according to their own morals they are bad people. Most people can pretend that they don't really have a choice or can't really change, but when they meet someone who has made these radical changes, they get confronted with the reality and get instantly defensive in order to keep the illusion intact that they are "morally good", taking out their own insecurity on the person that made the choice that they haven't made.