Why do some people get away with saying what they want and others don't?
To give an example; one woman I've known for several years, very outspoken, to the point of being rude, just coming out with things like she doesn't like your hair colour or she thinks you need to lose weight. Shouts at people like a fish wife if anyone upsets or crosses her. Everyone tip toes around her, scared of upsetting her. One day her daughter had been really horrible to someone else's daughter at school but she went up to the other girls' mum and gave her a massive row on the playground and reduced the other mother to tears. The next day the mum that had been reduced to tears was all smiley and chatty with this woman. Why??!! 
Another woman who is in a large group of friends I did go out for nights out with is similar. On some nights out she has been absolutely vile to one other group member in particular, so much so that everyone comments on it afterwards and says how horribly she behaved yet none of them fall out with her and they are all trying to stay in with her and arranging the nights out around what she does and doesn't want to do. Even the woman she is horrible to doesn't fall out with her and just puts up with it. I've stopped going on the nights out as it is truly sickening to see, and although I tried to stick up for the other woman several times, other group members told me to just leave it and not make a big deal of it.
I know people would fall out with me if I behaved like that and certainly wouldn't facilitate it. Not that I would want to but you know what I mean!