> Devoid of any kind of feelings towards anyone else, he shouts, screams, cries and sulks his way through his petulant life

Sounds like full-on Narcissistic Personality Disorder.

Various people who knew Steve have also said that he must have had this.

As far as I can see, it's probably true.

I don't think it's right to attribute malice to the man if it's the case. Neither is it right to insist that someone be prevented from being successful in business because they have something wrong with their brain.