The whole purpose of self defense is to AVOID danger. This means not getting into a face to face confrontation with some slimy street punk unless you cannot avoid it.
I have had this happen before (in the mall in Williamson years ago) and the thing to do is just go someplace, call the police and let them deal with Mr Flashy.
In a worse case scenario, if you were to challenge an idiot like Mr Flashy, you might have to shoot it out. That is to be avoided for two reasons.
• No matter how good you are, you might catch a round. Remember even great gunfighters of the old west like Wild Bill and Wes Hardin avoided shooting it out with other pros.
• Do you really want to go through all the crap a shooting usually entails such as a coronoers inquest, police investigations, hiring an attorney and sweating about some anti-gun politician and lawyers deciding to make your life hell?
Go read Sun Tzu's "Art of War" and pay close attention to where he says to choose your battles when you know you can win.
Sun Tzu probably would have waited till the thug turned his back and shoot him between the ears.....