Evil will always triumph when good people stand by doing nothing. This is not an original idea (don't ask me who coined the phrase, but I know I read it somewhere), nevertheless it is as true today as it was when first stated.
As a species we love to chatter, meaningless, futile, sounds emanating from our mouths... We love to moan and complain, espouse the problems of the world. How often do we stand around while evil reigns around us? With our hands over our eyes, over our ears, over our mouths in a parody of the three monkeys 'See no Evil, Hear no Evil, Speak no Evil' Oh, yes, we love to talk! But we don't like to do anything, get involved.
Maybe it's cowardice; we don't want to get harmed, move out of our comfort zone, put ourselves at risk... 'It's someone else's problem'. But what about that loved one, sibling, or even total stranger being harmed in our full knowledge, even maybe in our sight. No, it's not our problem, their are other people whose job it is to do something; the police, a social worker, just not me! Or maybe we just don't care!