People kill others for a variety of reasons, most which are incredibly foolish. Just last night, I heard about a woman who, when asked to leave a vacant apartment, beat the asker (another woman), then showed up the next night with a gun and shot into her apartment, hitting the woman. So, you have these people who, for whatever reason, either lack sense of priorities, have no control over their tempers, or just don't care about others. And you hear about them, because they're not the norm. They fascinate other people, because that is a world so different than ours that we can't understand it. We get caught up in questions about how he could do such a thing, how he felt later. There's entire sections dedicated to them.
What we don't hear about is the flip side. The people who do good things for others aren't written about in the news, because it just doesn't make a story that people will wonder about. What if someone gave another person an X-box they had so patiently waited for? It wouldn't make the news. People might say, "Oh, that's nice," but they don't remember it for long. It doesn't stick in their minds.
If it's really bothering you, maybe try to stay away from bad news for a while, or find a place dedicated to good news. There are some sites (like this one) that are just for that kind of thing.
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"Nothing worth having is easy."
Three years!