an agressive, untrained, thug is more dangerous then a guy with years of martial arts training. He is strong, fast, angry, doesn't care about life, and has probably had more real fighting experience then you (as in the martial arts student he is attacking).
I agree with Don.
Have seen too many ppl with years of training collapse because in all their years they were never taught to build and maintain a serious survival (or warrior) mindset that will be able to handle most aggressor mindsets and even some killer (asocial) mindsets. Often pure, practiced rage with a singular mind set on total destruction trumps years of training simply because as far as mindset goes, the person with "martial arts" training is bringing a rubber knife to a gun fight. They may have many more tools available than their unskilled attacker but their operating system has not been trained to use those tools under the conditions of a person bent on their total destruction.
This applies to folks who have guns as well. Many, when faced with a target who is moving and will close in a matter of seconds and start to pummel, stab etc. and inflict severe damage, the same confident target shooter is lucky to get off one shot on target, and often that shot will not stop a determined attacker from closing.
Just my thoughts - mind leads body, but mindset empowers action.