The Myth of the West is this ritualized glorified human sacrifice. Way old, coming from eons. Powerful stuff. Some special person, avatar figure, for instance St. Joan, dies for the good of mankind. Tragic, purging, dies for your sins. Glorious, excruciating.
So. Famous, beloved person gets assassinated.
I'm not saying the myth artifact is the cause, I'm saying it may be a factor. The myth artifact may be the reason such an act may have an inexplicable but absolute rightness to some people. Is there a pattern buried deep within us which could make a horribly wrong act feel inevitable? Lennon, Martin Luther King, the Kennedys, is this our Passion of Christ?
"Forget organized Christianity; forget organized Judaism; but oh . . . the passion."
----(loosely) paraphrasing Simone Weil