simple, bad people use the gullibility of the good-ol-trusting folks for their own means. If you have no morals you have no problem hurting others.
The good don't seem to mind since they often follow a philosophy of being humble and taking it lying down, somehow believing that the wicked will be punished after death and so do nothing to stop them. It takes more than a bad man to do evil, it takes good people to do nothing, see the holocaust in Europe.
Why don't good things happen to to good people? that is the real mystery here