"Who lives by the sword dies by the sword"

This cliche seems hypothetical to me, however, recently a friend of mine told me that whoever invented this words was a "genius".My last post was on irrational(phobia) fear and i promised i will talk more on the rational fear we always experience.Personally i am hydrophobic(fear of water), some people are claustrophobic(fear of closed space),others are ailurophobic (fear of cats) the list is long,infact psychologists nowadays tend to use just the word phobia for fear,since very few people nowadays study Greek. Anyway, to come back to my friend's presumptuous allegations, 'to say so',i find the word quite irrelevant sometimes.People have different fears as i just mentioned some above, but this case seems peculiar to me:-i finally found that this same friend of mine is afraid to drive because he believes that drivers have a high probability of dying on the road than just the passengers(who lives by the sword dies by the sword),he further gave me an example that those possessing guns are more likely to die than those without(i think the opposite is true) i still have to know the source of his statistics.may be psychologists should one more time come with the proper word for this kind of fear.I tend to think that the correlation between risking your life and getting away with it is quite ambiguous, just like saying that people who do jobs they have a passion for excel(Gets rich).Anyway let's leave that for a debate.Why actually should somebody fear a coachroach and not a lion.This is one of life's mysteries, for real.What's your take on this?