It is reasonable that crazy people would be on SSRIs though. Blame the SSRI (or gun), not the individual. We all are looking for something to blame. Crazy is good enough for me.
Do you know how an SSRI works? Because if you do you realize that the potential for even a mostly stable person to go completely insane is very high.
If the Seratonin level suddenly drops in your brain and you're having a bad day you might kill someone, literally.