In fact, I think it's often used simply by people who resent another person for making them feel inferior, if that person expresses anything but outright and total humility, and instead any degree of pride, in who they are and what they've done.
I mean, everything is relative.. Truly. Your question to how backstories change things is absolutely necessary because it helps make that distinction. TSA parking people aren't bitchy and rude.. they almost have to be that way for their job. Someone throwing clout around isn't doing that to be a narcissistic ass automatically. There takes a degree of taking the environment and background into consideration before you just assume your boss, teacher, or that new gal to the group is just full of themselves.
What is a kind of thing that someone would do that is narcissistic that you would "need to step in for"?
Maybe this is getting overly analytic for me.. but for example. I had a boss that was really just full of herself at one of my jobs. She would tell us (all the staff) in meetings how hard she worked for us, and how meticulous she was. In reality, she showed up late frequently, I had to pick up a lot of her slack to keep things running smoothly, and frequently she was just surfing the internet when she should have been working--just locked up in her little office trying to make the time pass by. She really believed that she was a hard worker, and there's nothing I can say that will change that necessarily. But. That doesn't mean that I had to put up with always being stuck with her shit.
So, during times where it was personally affecting me (i.e. Me staying at a god damn yogurt shop until 2 am just so this girl can sleep in the next day) I pulled a witness in, and gently and firmly explained that I was NOT going to do x because it is in her job description and it's part of her job.. She gets paid more because its harder work, and if she wanted me to do her job, that's fine with me, but give me the pay increase to go with that work. I don't mind helping out occasionally. Everyday? I'm not a doormat. She tried to steal my sunglasses because she felt mine looked better than hers did (they did. My sunglasses rock.) and I had to pull a witness in to tell her "Hey.. You cannot go around telling female employees they should be more careful with money because 'girls like money'. It's hard to tell someone to pay attention to detail, when you yourself admitted that you mistakenly took my sunglasses instead of yours, even though the two look nothing alike." She was a total narcissistic ass to many young high school students, and I felt bad when I had to leave that job because I was really the only buffer between inexperienced kids and this girl up until that point.
So, if you're asking for super douchey stuff, that's what I perceive it to be. When they're just being narcissistic like "OH, yeah, I look so good today." I don't care. But when they think they're hard workers at a job where they don't work hard, AND it's affecting me and my team.. I step in. And I make sure to bring a witness, so that if she gets defensive (which, she did) and tries to wig out.. It's much more difficult for her.
There are plenty, plenty, plenty of people who think I'm a total bitch. Literally every single one of my soldiers thought that about me when they first met me. It's natural to react to confident people who aren't immediately scared of authority. But there is a line to be drawn, and narcissism is labeled as a disorder for a reason. You have to know how to handle situations as they come. And, in my opinion, if someone's narcissistic behavior interferes with something I'm trying to do, I'm not going to hesitate to push back and take them down a notch. They need it. But the proper way, and picking and choosing your battles, is necessary with this sort of disorder. It's a delusion. You can't fight a delusion on your own. One person saying you're crazy does no good. Another person there, that they know they should have respect for, that changes the game. And they become more reasonable in that moment. Even if they don't like it, or believe it, they'll say things more reasonably.. and more importantly.. they'll leave you alone.