Why do people trade Love for Hate?

As a person that has led people ever since I was eighteen, and have always strived to learn more about people so I could better lead. I know I'm not where I want to be as a leader, but I'm learning and growing every year. There is one thing that I have noticed in a small group of people that I just don't get (I'm Lost) I try to understand but just don't get it! What is it? It's the action of walking away from everybody and everything that is loving and good and chasing people and things that are not.

You might be saying "people don't do that!" but I would say with confidence that they do, and it's happening every day. Anybody that cares about people has seen it a number of times and no matter if we know that person personally or not, it breaks our heart. So many people suffer from this and even know the number of people that do this type of thing is a minority, it affects everybody at some point in our lives, if not directly most definitely indirectly. So what does it look like?: It's the parent that neglects their child/children, the child that rebels against their parents, the spouse that abandons their husband/wife, or the person that walks away from their entire family, to name a few.    So what makes these people they are moving toward harmful? That's easy. Anybody that allows you to walk away from a loving and nurturing support system is not only harmful but hateful, not only to the loving support system but to you! If they were truly caring and loving they would support and encourage the continued relationship with the people that love you. I don't get it, maybe because, even know I've done lot's of things I wish I could change or do better, I have never walked away from a loving support system or loved ones, and I most definitely wouldn't have done it in favor of a person or group of people that showed contempt toward my future. So I ask why? 

If you are more enlightened to this situation than me please share and comment to help me understand why this happens. Maybe you were that person, and were blind to it and now you see, whatever it might be please share anything you believe will help understand and help families and individuals deal with this tragedy.