In the end, it all comes down to whether or not you have faith in humanity.
Well, in the past century we had the worst acts of genocide ever committed, millions of people slaughtered for the crime of being who they were. In many of these atrocities, those with power to stop it allowed it to go on without much more than official disapproval. We began this century with some folks thinking it would be a great idea to fly some jets into buildings, killing unarmed and helpless people; and the US responded by killing a bunch of unarmed and helpless people, as well as the occasional armed soldier. Those were probably "collateral damage". And the genocides and famines continue without much interference from anyone.
Without wishing to sound in any way pessimistic, there are times when my faith in humanity is not rock solid.