How could they?

I don't understand people anymore. I don't understand why some people have such a need to fulfill their pleasures. They are so desperate, they will do anything in order to satisfy themselves. I don't understand how one human being can hurt and ruin another person's lives just for their own benefit. How could such people exist? Every human being on this Earth is so delicate, our lives and souls are so delicate. One can only withstand so much pain in their lives, no one in this universe deserves to be disrespected, in anyway. Every single one of us have a purpose in life, but the ones that damage that purpose for others, are the obstacles in this world.
Why would you ruin someone else's life for the benefit of your own pleasure? How sick can one human being be to do that?
I don't understand it, I never want to dwell into the minds of those that enjoy hurting others. It seems as though their thougths are twisted, somewhere along their life, their mind was twisted.
I feel like a kid again, asking so many questions as to things I don't understand, asking what may seem like difficult questions to answer, but to those who know, it may seem easy to.
I don't see any good reason to make someone feel like they are worthless, while one feels stronger. So many forms of abuse, at least everyone in this world has gone through at least one type. But there are some forms that are cruel, there are some that only the trully desperate and trully low individuals can accomplish. I pity them, for they will meet a consequence far more damaging then they have done.