One of the etymological roots/definitions for sarcasm is "to tear flesh". It is biting, caustic humor. I teach English and we talk about the difference between sarcasm and verbal irony; they are not the same thing. Sarcasm generally is rather mean or "biting" in its purpose and can be really offensive if directed at a person or an issue they have strong feeling about.

We have to learn when and with whom sarcasm is appropriate to use, and when we need to keep our tongues in check so as not to be offensive to people. That's just part of learning to communicate with others effectively rather than turning them off completely. It is also a matter of respect for those around us.

I have no problem using sarcasm around my oldest son, for instance, but my youngest son doesn't always "get" the sarcasm yet AND he is just more sensitive by nature to that kind of humor. Out of respect for him, I temper my sarcasm in his presence and save my sarcastic jabs for those times I am around my oldest son who completely "gets" sarcasm.