Actually narcissists and sociopaths don't suffer from their ailment.  That's the main reason they rarely seek treatment, and rarely change, with or without treatment.  Unlike people with depression, schizophrenia or Borderline Personality Disorder, they are just fine with the way they are (although they may not like the consequences of their behavior).  And unless you're already a sociopath or narcissist by late adolescence (there's a reason these are called Character Disorders), you're not going to become one, so staying 'on the sane side' is not the issue.