[akomtu]

If nearly everyone suddenly became selfless saints who never defend themselves, because they know that evil cannot extinguish evil, then the few remaining predators, who enjoy invoking fear in others, would turn this selfless society into hell. It seems to me this paradox cannot be resolved other than by separating the good part of humanity from the evil one, which isn't possible while there's a sizeable grey area in between - the undecided ones.

[sottol]

Or the police could do that but somehow they can't seem to.

[akomtu]

Police serves a different purpose: it protects the society order as a whole, it's a defense against anarchy. For personal security you'd need to hire someone with authority to kill, a member of the police basically, but that's not an option unless you're rich. In the US not only rich are allowed to have personal security.