This is one of the most important questions we can ask in our current seemingly crazy world.
IMO, it is this way because "the news" is big business... and 'good' doesn't sell the way 'bad' does. Once we accept that and stop letting "the news" control the way we view the world, then the world doesn't seem bad at all. The reality is that most people are good. Most things that take place in this world are good.
Through an amazing stroke of unfathomable luck, we find ourselves with life; the only one we will ever have.
But then, we learn a negative view of the world through the sensationalized portrayal of our collective lives. We are naturally more curious about the uncommon evil than the common good, precisely because it is uncommon. Unfortunately, "the news" companies know and leverage this in a big way; spending all their effort rooting around for bad stuff to tell us about. It's much harder to find than the good stuff, but the good stuff is just too mundane because it is so common.
"The news" has become a lens through which we see the world. The more we pay attention to "the news", the more bad we see, because that lens is focused on the bad. The less we pay attention to "the news" the more good we see; simply because there is much more of it.