No kidding. For every loner who goes ballistic, there are millions who never harm a flea. And sometimes there are the ones like the BTK killer, who have wives and kids, upstanding member of their church, have respectable jobs and all that, and it turns out they have an ugly secret.
Yes, and I think trying to develop profiles for serial killers and mass murderers and other extreme criminals is mostly a waste of time. As you illustrate, whatever profile they come up with, for every one that commits an atrocious crime, tens of thousand, or hundreds of thousands, or more, of others who fit the profile never commit a single aggressive act, let alone a violent crime.
You could add the guy in Canada. He was a high ranking officer in RCAF, but was a serial killer at the same time.