I understand that this could possibly be true and Martin was a hot-headed teen who thought he'd teach Zimmerman a lesson. However, there is an equally plausible, and
more believable, argument to think otherwise. That Martin was an unarmed teen, walking home minding his own business, when he noticed he was being followed in the dark by an unknown man. This man then got out of his vehicle to follow him, may have confronted him, pointed a gun at him, or grabbed him. It's entirely reasonable to assume Martin felt threatened and thought he was in a fight to defend his life.
For those who will say this argument is not more believable, step back from your opinion for a minute and look at it rationally. It is not normal behavior for humans to suddenly decide to attack someone to prove themselves or teach them a lesson. It is possible, yes, but highly unlikely. Martin was not out looking for trouble, he wasn't with a group of friends and thought this would be a good opportunity to prove his manhood. He was obviously scared and nervous, per the conversation with his girlfriend; this doesn't sound like someone who would attack a person to "prove" himself, but rather the actions of a scared person who didn't know what Zimmerman's intentions were.
Also, if Martin was really planning to attack, it's unlikely he would still be talking to his girlfriend on the phone when the altercation started. He would have hung up his phone before throwing a punch. The fact that he was still on the phone with her and she heard it drop shows that something happened suddenly, such as being grabbed by Zimmerman or having a gun drawn on him. It doesn't sound like a planned attack, but rather a reaction to something.
Of course, some will believe otherwise and nothing will convince them that Zimmerman was responsible.