Fundamental attribution error
Have you ever gone to a grocery store the day before a big winter storm is supposed to hit? Did you see all those idiots shopping in a panic? Some are even picking up three loaves of bread and two gallons of milk! I mean come on! It's not like this is the end of the world! You live in a major metropolitan area: You don't need to stock up and go into survival mode.
You, on the other hand, simply went shopping like you normally do. Sure, it was a day earlier than you were planning, but you were almost out of bread and milk, and didn't want to have to get out tomorrow when it was all icy and dangerous to drive.
A few years ago I learned the name of a very important phenomenon: The fundamental attribution error (or "correspondence bias", if you think is more accurate). It boils down to you believing you have valid and well-thought-out reasons for doing what you are doing, but other people don't. You are reacting rationally to the external world, but those other people? They are doing things because they are mean, flawed, corrupt, or some species of idiot. You know your situation and reasons, but you don't know the other person's situation and reasons: they are just bastards or morons.
You are simply picking up a few things at the store before a storm, or maybe even just doing your normal shopping, but those other people are panicking.
You didn't have enough time, so you stopped at McD's drive-through, those other people are lazy fast-food addicts.
You are merely sharing information with your friends, those other people are petty gossips.
You are struggling with your personal vices while external events make it difficult, but those other people are weak and always making excuses.
You were grumpy and short with people today because your cat died, you had a fight with your spouse, your printer is broken, you lost at Candy Crush, or a whole host of other valid, personal reasons. But that grumpy waitress…?
She's just a bitch.