Self-loathing is an extreme form of poor self-esteem. It is the sense of loathing one's self -- a common complaint from people with poor self-esteem. Many people who get to the extreme of self-loathing become self-defeating -- even self-sabotaging. This is the prize one wins if one can sustain a really poor self-esteem for long enough while being emotionally abusive to one's self.He has to want to be happy to get well, to change his life, because all the worrying and talking to him won't do any good if he's not willing to listen and not willing to do whatever it takes to make himself happy.In order for us humans to be happy we have to have a purpose, we have to know what we are doing with our lives, we have to find our way in life. Some people get this at an early age and some find it later. Everything he is doing is self destructive and his parents are enabling his behaviors by allowing him to live at their house, smoke pot in their house, and not being a contributing factor to the household or family.My suggestion is that you call your local mental health department in your county or city and find out how he can be seen there, if he's not working he can be seen there on a sliding scale. He needs to address his hopelessness, self loathing, and drug use. Get this information for him and give it to him written down on a piece of paper and then you are done. You have done all you can because you can't make him go if he doesn't want to. If you don't have a local mental health dept which you should, there will be health clinics in your town for low income clients and they have a sliding scale too. Good luck