I also would not disregard the possibility that some of GZ's fear was fueled by his wife (not sleuthing her that is wrong). But I could see how a man with a wife that was fearful that some young aggressive male might break into their home and attack her would fuel GZ's suspicions and put him in a more aggressive mode. The 911 calls confirm her fears. Understanding that wanting to protect your family is a strong motivator it does not have to become an obsession which GZ appears to have been dealing with. jmo
It could be any number of things. Perhaps he was picked on early in his youth, predominately by black males? I have no doubt that he was fearful due to the robberies in his area. There are probably thousands of people just like him, with that kind of fear. The difference of course is most of those are not empowered with a gun, acting as 'neighborhood watch'.
My answer to that would of been....move.