He cannot change his behavior, nor find any reason to. He is a Malignant Overt Narcissist, and always will be. There is no cure, and treatment must be sought.

I don’t think you are correct in your assumptions. I think DT has narcissistic personality disorder or some allied condition...he actually does think he’s a genius and better at everything than anyone else. He can’t recognise that his behaviour is anything but completely correct. People who are opposed to him are fair game for ridicule because he’s following his own instincts of superiority to act that way....and he’s never wrong!