On Free Speech and the Pointlessness of Coercion

In most countries, making threats is a crime.  But why?  Say for instance that I tell my friend Gus (I have no actual friends by this name, so this is safely hypothetical), "I'm going to kill you, Gus."  Why should this be a crime?  If I do not have both the intention and the ability to kill Gus, then the threat is nothing but empty words, and completely pointless - whereas, if I do have both of those things, my ability to succeed in killing Gus is only diminished by my providing him with advance warning.  The logic behind these laws seems to be that Gus deserves not to have to live his life in fear of the possibility that I might kill him...but why should he give any credence to my threat if I make it?  The odds that I'd mention killing him but not actually plan on doing it are certainly not any better than the odds that I'd plan on killing him but not mention it.  If he is credulous enough to believe my bald-faced statement is factual, then should he not be more concerned about all the people who might harbor secret grudges that they've never verbalized?  If I were Gus, I'd be more inclined to worry (to the point of paranoia if need be) about lurking assassins under the cover of false friendliness, than to take seriously a probably-joking statement from someone I know, or a completely out-of-the-blue threat from a stranger.

Coercion of any sort is ultimately pointless, since human beings have the ability to lie and they always will have that ability.  If I say "Gus, if you don't get out of my house, I'm going to kill you", and Gus gets out of my house, I am still perfectly capable of killing him despite him submitting to my coerced demand.  Anyone who can act on a threat can do so regardless of your actions, which is why if anyone ever offers me the choice of "your wallet or your life", I will leave the decision up to them as to whether they actually want my wallet badly enough to search my corpse for it, because I'm not about to advertise its location and then risk them deciding to kill me anyway.  All of this works just as well for bribes as for threats; if someone does as you ask, you can still easily refuse to pay them the agreed-upon sum (particularly if you are willing and able to kill them).  Thusly, either positive or negative coercion is entirely pointless, and statements suggesting it can be freely ignored.

Ultimately, the sooner all of humanity wraps its collective brain around the idea that talk is cheap, that words are not reality, that in short we are a species of filthy stinking liars and always will be, the less energy we'll waste on thoroughly pointless activities such as policing people's speech.