Very interesting post. Last year, I found a psychopath (now I would call him) online. He was gay and he became my 'best friend' just to use me. He made me write his whole bachelors thesis because he was so 'disturbed'. I wrote for him because I was deeply into the friendship. He also asked me often to send him money as loan, and so I did, and he never returned it. When I asked him to return the loan, he simply blocked me from facebook. During our 'friendship' , he was constantly torturing me. It was terrible experience. So he not only scammed me, made me write his whole thesis, but also was never grateful, and constantly telling lie. He was also narcissistic, always admiring himself. My husband also knew about him, and he told me to stay away from him, but I had so much sympathy for him at that time. So the end of the story: When he blocked me, I starting sending him emails, and after 6 months, when I told him that I have earned lot of bitcoins (In January 2018), he suddenly replied and then we started chatting. He said "share your wealth" when I said I have bitcoins. I had revenge in my mind. I told him everything about him, how I think about him, etc, and then I blocked him forever. And, when he was 'using' me for his selfish motives, he lost his money too, in online revenue sharing program. So what he gained from me, he lost 10x more than that. The only harm he could give me was wasting my time writing for him, and giving me lot of stress while in the relationship.
He had a terrible childhood, that may be the reason he became a psychopath.