Do you think having manners hurts a person and makes them a victim?

For instance, people with less manners can bombard you with surprise insults. And someone with manners may not know how to react. Also, they may hope for a civilized world or they maye expect a civilized world, and not be fully prepared for the rudeness of the world. In that sense, what good is it to teach manners to a child if its just going to make them a doormat for rude peoples behaviors?