You only have to look at the havoc wreaked in Afghanistan by a soldier who 'lost it' to know that in all walks of life there will be folk who occasionally lose the plot. Luckily cabin crew are not generally armed with anything more dangerous than a bar trolley. Now where did I put that fireaxe?
Actually I do think that CC should be subject to an annual medical instead of self-certifying our fitness to work. I have met a few over the years who really shouldn't have been allowed out on their own.