That's not the topic of this tread.
Of course, if someone is in your face and you have to defend yourself, then you may have to do so, and fight as best you can, keeping in mind that there is a difference between self defense and assault and battery. If you are the perpetrator, you will perhaps be engaged in some very long legal ramifications.

As to the thread topic, I personally ignore conversation that I am not directly a part of while in public places. And to THIS point, life can be full of conflict or peace. And thus the choice is yours.