This is the sort of person who needs to be watched a lot.
This is not a lazy person, or a person who needs a kick in the butt, this is a person who is mentally, emotionally unable somehow to function in the world. He is going to have a very rough next forty years and is liable to go truly nuts at some point. His parents may have done a bad job, but maybe not. He may just be a klunk.
Either way, do not sell this guy an AR-15.