When dealing with any kind of angry or obnoxious person this is psychology is a nutshell and sound advice. Once you understand a person’s behavior towards you is most often a reflection of their inner battles (unresolved issues, trauma, mental illness…etc.) and has nothing to do with your value as a person then confrontation and/or awkward social interactions becomes less stressful. Even if it doesn’t involve you it is easier to observe and react with a calm mind knowing it’s them, not you, that has a problem. This only applies to person’s emotional state or inappropriate responses and doesn’t alleviate us of responsibility if we acted (or failed to act) in such a way as to make them angry, annoyed or whatever. It also doesn’t mean we should tolerate abusive or overly-aggressive behavior either. However it’s still the right advice when another person is on the attack against us or being inappropriate in some way, we can remain calm knowing they are probably be dealing with a lot more than we know.