I understand what you are saying, but if I go and start punching a random stranger in the street, he starts beating me up instead, I do not reserve the right to kill him because I feel my life is in danger.
Obviously........................... and like I've said about 100 times now, if Zimmerman assault Martin first or otherwise overtly threatened him after following him it is not self defense.
I'm not talking about a situation where someone is getting yelled at and they decide to sucker punch them. I am talking about someone that is getting yelled at, fears that he is about to physically attacked and has no option to retreat, and defends themselves.
Only very rarely does that justify assault. There almost always has to be another complicating factor... like the person being belligerently drunk, otherwise out of control, having a weapon, having a history of some sort, just having assaulted another person, etc.
How do I come to this conclusion? From parents getting into fights at little league games. I know that when someone verbally threatens another person "I'm going to whip your *** in the parking lot after the game!" and you have every reason to believe that they mean to follow through on it, that you
do not have the right to haul off and hit them first. Just a fact of the law and I think it extends to most verbal threats/perceived danger.