Actually, it's not constant. It's decreasing.
Check for Steven Pinker on violence. The further into the past you look, the more violence you find โof any kind. Go back to the period where we lived as hunter-gatherers, in Harmony with Nature, and suddenly nearly 2 men in 3 die at the hand of fellow humans.
So, while History does show an everlasting presence of violence, it also shows that this is not hopeless: slowly, steadily, we are making progress. I'd keep an eye out, though: we're not there yet, and each death still is one death too much.
Humans are never going to be so perfect that 0 men out of 1,000,000 dies at the hands of another. Hell, humans are never going to be so perfect that 0 out of 1,000,000 doesn't deserve it, either. And I don't even want to live in a world where people are above enjoying a good boxing match or a bloody movie.
I'm not sure the second paragraph is hopeless. Sure we probably don't want a world where we're so perfect, but we also may not need one to prevent violent death. We could for instance imagine something like mechanical guardians that simply prevent any fatal move to ever occur (like, nano-machines in the walls that just spring up to save your life whenever needed).
That does suppose a level of technology that is extremely risky by itself, but provided we solve a few problems, such as Nanotechnology and Friendly AI, it could happen. Heck, we could even reinstate blood sports, only without the "death" part. (Okay, those problems are faar from solved. But I haven given up hope yet.)
Violence is also a constant presence in world history. No society has ever fully eradicated violent crime, and no era has ever fully eradicated warfare.
The news media is popular entertainment. Yellow journalism has also been a constant. It's far more cost-effective than honest journalism.
As I've gotten older I've found it's nice from time to time to disengage from the darker parts of reality and enjoy innocent things. But the appeal of violence is an essential part of the human condition.