The Horses Mouth
“Most frum people will stop doing an aveira if told they are sinning.”
Oh if only that were true! If only!
Try going over to people who are talking in shul during Chazaras Hashatz, Kaddish, krias Hatorah and tell them that it is assur to talk. See where it will get you.
Most things people do wrong they know it is wrong but do it anyways because they have a yetzer hora and others are doing it too. We tend to rationalize especially when we are part of a group. Nobody wants to be a frummie and sadly for many keeping basic Halacha like strict Tznius or not talking during Davening, watching movies…makes one a “frummie.”