The use of humanity

Many of lifes attitudes are set by experience, environment and teaching. I would like to consider myself generally rounded in all of the forementioned labels and it is for this reason that I wonder sometimes on humanity's failings.
I understand the need for differing attitudes and personalities but when it comes to simple humanity I see many failings in many people. I wonder what place there may be in life for a person that could callously walk along a street and on coming across a simple feline sitting quietly on a step would find it enjoyable to kick the animal hard enough to break its ribs and send it hurtling through the air against a wall.
There was no provocation on behalf of the animal which I can attest to as I walked barely twenty feet behind the perpretator but still he took delight in harming this poor animal. Not content with causing harm, the creature walking on two legs laughed and enjoyed the process as if watching a comedy unfold.
The actions of my own are to be argued against as my rage boiled over and I sought revenge on behalf of the small grey mammal. On approaching the man, he was predictably coy on what he'd done and somewhat aghast at being pulled up on his actions. He did not show anywhere near the same bravado when confronted by myself and when I left him the tears welling in his eyes accompanied a plead for leniency. This angered me even more!
The man left and I removed the cat to the nearest veterenary clinic. The feline recovered and was returned to its owners.
It left me however with an unbelieving of how a presumed higher evolutionary mammal could delight in such actions. I can see no reason for these types of person to exist among us. If incapable of controlling ones own emotions or dislikes suitably that would see no such actions then I see no reason to allow them to be part of our environment. It is of no advantage to humanity to have such people roaming among us. They are undeveloped in matters of emotion and caring and only add to what is already an extraordinary and troubling society.