To serve as an example, here's my personal list:
1. Highly insecure people who bring others down just to "feel better" about themselves.
2. People who explicitly take actions based on jealousy.


Sociopaths.

These are people who have little or no sense of empathy; they don’t care if they hurt others, as long as their actions promote their own agenda. These are people who, when they see someone else in distress, really deep down don’t care.

I had known such people for most of my life, but hadn’t truly recognized them until my sister (Ph.D. in psychology) gave me a book called The Sociopath Next Door (by Martha Stout). I highly recommend this book. Most people can name the famous sociopaths: Hitler, Stalin, Mao, Pol Pot, and Putin. But it is very helpful to recognize the less well-known ones, the ones you come across daily in your personal life.

Many sociopaths have learned to be sweet and to appear to be kind, but that is a mask for their inner standards. Doing so helps them exploit others. Several percent of the people you meet are thought to be sociopaths. The percentage may be higher among “successful” people, since there are some survival advantages to the syndrome. There are also disadvantages. One sociopath I know quite well won a Nobel Prize in physics (in part due to taking credit away from others), but despite that, nobody who has ever worked with him in the past will work with him again. Largely as a result, his post-Nobel career has completely stalled.

These days, when I encounter a sociopath, I treat him (or her) with politeness, but I am careful to have no substantive relationship. I do not allow myself to depend on him in any way whatsoever, even if I think it is in his best interests to help me. Life is full of opportunities, and when you run across a sociopath, your best approach is to find a new path, one that avoids all interactions with that person.

It is surprising that sociopaths exist? It may be a physical/medical/inherited condition, not easily cured through psychological counseling. I think the real miracle in life and civilization is that the vast majority of people do care about others. I don’t have the sense that this large scale empathy is shared by most of the members of the animal kingdom (outside of empathy for their immediate families and their providers; animal lovers will probably furiously disagree, but remember: I am allowing for pet empathy towards their providers.)

Even in humans, empathy is sometimes limited to the tribe. Outsiders are not considered to be human. The most remarkable teaching of Plato and Jesus is that one should not only love one’s neighbors, but also one’s enemies. To the extent that we don’t do so, we are all somewhat sociopathic, if only a little. That should help us understand the true sociopaths. In effect, they consider all their colleagues and acquaintances (and often even their own family members) to be their enemies. How would you act if you were surrounded by enemies? Would you simply turn the other cheek?

Based on what I have read about sociopaths, and based on what I have observed (in debate, in interviews, in talking with people who have suffered by his hand), I believe that Donald Trump is a sociopath.

Source: QUORA