TUA Universe Mysteries: Mack's Insanity

This is a TUA Universe mystery that relates to Mack's insanity in the novels and how he had turned into a psychopath, when he was originally a heroic character.

The mystery itself.
How did Mack suddenly go insane so quickly? Did he see something really disturbing and got mentally scarred? Was he insane since he was born and just hid it until now?

Theory Responses.
As of right now, there are no theories that explain why Mack had gone insane.