What do people gain from killing others?

Everyday I hear of people being killed for senseless reasons. What does someone gain from killing another. I've hear of people being killed for minor things such as - being in the wrong neighborhood - bumping into someone - stepping on someones shoes - arguments and minor confrontations. These are not reasons to want to kill someone over. It's just sad how we treat each other. Personally it's fine for us to argue or even fight hand to hand if it must come to that. But it should not get to the point of taken someones life.

Lately there has been many mass shootings. I hate hearing things like this. Recently at the Garlic Festival where kids got killed. It's truly sad.

- I just want to hear your opinions.