According to a paper by Manual Eisner, kings had a rather extreme violent death rate:
This paper examines the frequency of violent death and regicide amongst 1,513 monarchs in 45 monarchies across Europe between AD 600 and 1800. The analyses reveal that all types of violence combined account for about 22 per cent of all deaths. Murder is by far the most important violent cause of death, accounting for about 15 per cent of all deaths and corresponding to a homicide rate of about 1,000 per 100,000 ruler-years.
Further, there is 'positive autocorrelation' in murder rates, in that if you murder a King to take his spot, your probability of being killed is above trend. Thus, to commit regicide puts you in the rarefied air 10 times that of the most murderous environs on the planet.
One can see why the primary virtue of the nobility has always been physical courage, demonstrated most recently when young Prince Harry eagerly signed up for dangerous missions in Afghanistan, and has the benefit of merely being a function of will. Modern warfare and information technology has made such bravery as irrelevant and absurd as it should be for determining our class structure.