I am much more interested in what was going on with this guy. Appears to be a psychotic episode, and if so, brought on by what? In high school, PCP was a thing

I am much more interested in what was going on with this guy. Appears to be a psychotic episode, and if so, brought on by what? In high school, PCP was a thing and would generate stories such as taking a wine bottle to the head without effect. Maybe it's just morbid curiosity, but I fly a lot and am as concerned about mentally ill passengers as I am anything else... If he had a tendency to behave this way, or a serious mental illness, was there any way to know before he boarded a plane? Did he take a prescription med and have an unexpected side effect? Or was it illicit combined with profoundly bad judgement? Or did he just have a really bad day and decide to end it and take a plane load of souls with him? Hoping there is follow up on this story with an explanation.