First off, you are a wolf. People are all the same, and those who are labeled as sheep are just wolves who never had the chance to find out who they really are.
I lived many years as a drug-addicted musician in Los Angeles, and spent part of my life moving through a nightmare consisting of other drug addicts, violent criminals, mentally ill homeless people, gangsters and street level dealers of many ethnic identities. Many different ghettos. I survived this without becoming a corpse or an inmate.
When dealing with wolves, BE RESPECTFUL. They, more than anyone, operate on this level. Treat a wolf the same way you would like to be treated.
BE REAL. Wolves, more than anyone, can tell when you are being fake. Act the same way you would like other people to act with you.
DO NOT JUDGE. Wolves have a visceral reaction to this. Treat them the same way you would like to be treated.
BE HUMBLE. Wolves do not tolerate people projecting false pride. Act in a manner that you would find admirable.
DO NOT SHOW WEAKNESS. Wolves react to the scent of blood. If you are not bleeding, there is absolutely no reason that you need to smell like blood.
MAINTAIN YOUR EQUILIBRIUM, AND DO NOT REACT TO WORDS AND EMOTIONS. Wolves respect someone who can be centered in who they are.
PAY ATTENTION. Wolves appreciate it when people take them seriously and interact with them on a human level. Show that you are aware, and make the effort to express yourself honestly, without setting yourself apart from the pack.
DO NOT POSTURE OR MAKE THREATS. If you do this, you would have been much better served by taking some kind of action.
DO NOT TELL PEOPLE WHAT TO DO, OR HOW THEY SHOULD BEHAVE. Just don't.
KEEP YOURSELF TO YOURSELF. If you feel that you need to do something about what you see or hear, do not let anyone know what you are up to.

And most important: Realize that there is nothing separating you from these people, other than experiences and intent. You are just as capable as any criminal. In this world, anyone can become a victim, but with understanding comes power.
P.s. I have met doctors and lawyers who are just as bad as any "gangster". Never judge a book by it's cover.