Of course this is all based on the assumption that subjective reality is real. If you don't believe in it and you believe in the laws of probability then it's not going to make much difference to the chances of it happening.
But of course it's certain that learning Martial Arts will make you ready to defend yourself against such violence. I remember reading one of Steve's articles once - talking about Tai Kwon Do and how his reflexes became faster to the degree that he was acting without fully thinking. Definitely sounds like something you would want to have against a mugger. Your average thug or thief ain't gonna have a chance against a fully trained martial artist
