Don’t let anybody tell you a street fight is not an attack on your life.
“A street fight is an attack on your life,” I tell you. Don’t believe me? A homeless man died yesterday in Manhattan after being “shoved to the ground” in a fight with another homeless man. People routinely die after being punched during street fights, or just sucker punched. It is quite possible to be killed by the force of a hard, bare-knuckled punch to the head. It is also quite possible to die by striking your head after someone pushes you to the ground. It is also possible to die in many other ways while being physically attacked by someone who is using nothing but their bare hands.
If someone attacks you with their bare hands—punches you, chokes you, slams you to the ground—you should do whatever you have to do to stop them. If you have to stab them or shoot them or hit them with a brick repeatedly, that’s what you should do. That doesn’t mean that you should automatically kill someone who punches you in the face; it means that you should do what you need to do to stop them from attacking you, and, furthermore, it means that you should not underestimate the threat that “just a street fight” poses to you and your health. If someone decides to physically attack another person unnecessarily, and the person being attacked picks up a nearby 2x4 and hits them and kills them, well, that’s one reason you should not physically attack other people unnecessarily.
Fighting is bad so do your best not to get killed (and then after that, do your best not to kill anyone).