Someone ferociously lobbing insults at you through a computer screen is quite different from some ferociously charging at you with a knife. You actually get the option to choose whether or not you want to give a damn about it or not. Words by themselves are simply a collection of pixels or noises depending on the medium, the words only have meaning when we give them meaning (This explains the phenomenon of sarcasm). You deem the words harmful and they will harm you, if not then they are just a collection of letters, unlike a knife which is a knife with no questions asked, and it hurts when someone stabs you with it with no questions asked.
In the case someone does decide to physically go at you because you're a brony, do what you need to do, but if they're just firing 4 letter words from their mouth or furiously smacking away on the keyboard a good few miles away, they are simply not worth your time.