I think watching videos like 1lunatic1icepick and 3guys1hammer is good for you.
Watching these kind of videos brings you back to reality and makes you realise that the world isnt how people think/want it to be. They really do let you understand that people like this do exist in the world and you can never be too careful. It also makes you appreciate your safety and makes you thankful that you havent experienced this kind of violence first-hand (or Maybe you have).
Also it makes you desensitised to gore. Because lets face it, sometime in your life at least once you are most likely going to find yourself in a situation where either you or someone else is injured severely and how you react in this situation is vital. Say if your friend has snapped his leg with the bone ripping thru an artery, if you did not act fast enough he could bleed out. While all your friends who are afraid of gore scream like pussies you act like an alpha and compress his leg to stop the bloodflow.