I've hit about a half dozen guys in the trachea. None of them have died.

Mostly, they are as described above, in total shock, which leaves the opportunity to finish them off.

The worst reaction I've elicited was "knocking the wind out" type of effect that ended the fight. They choked, sputtered and couldn't breathe. If you're lucky, this is the desired effect of hitting someone in the throat. But, again... that's an opening gambit. They really shouldn't be given a chance to see it coming.

You shouldn't be fighting, in general, anyways. If you aren't planning ahead to avoid violence, you're doing it wrong. You should be packing, if you are in need of self defense. I've won plenty of fights, but injuries last a lifetime and you only have to lose once to die. Trust me, it isn't worth punching some asshole in the face if you're going to feel the pain in your hands for the next 50 years. It's not worth choking someone out if you tear your rotator cuff in the process. You feel some things for the rest of your life.

Good security starts with a dog, a pistol and a long gun.

Mace is a half measure. I can handle mace long enough to get to you.

A knife is a half measure. Nobody wins in a knife fight. Knives are for opening gambit moves. Kill by surprise. If you are forced into a knife fight, focus on "timers", places where a small cut will result in blood loss enough to end the fight. Inside the arm, just under the armpit, inside the leg, under the groin, the throat, and the top of the head. A small knick on the top of the head with a very sharp knife will blind your opponent with blood and take them out of the fight.

Either way, don't rely on half measures. Don't fight. That's the best advice.

If you are planning on being in a fight, always have back up. Certain things, they won't show you in movies or on TV. A deadly choke out is one thing TV and movies will never show you exactly how to do... just the general idea.

Same goes for neck snapping. The best way to snap someone's neck is from behind. You do not turn their head left to right. I, myself, was under the illusion and I tried it on a guy who shot at me in Texas. My brother, who is larger and stronger, tried after I didn't get it... but he tried like ten times. The neck did not break.

Later, I learned the correct way to do it, is to turn the chin up to where the forehead is. The perfect technique is that you use someone to distract them, in front, you kick their knee in from behind, causing a drop, while you grab their chin with your dominant hand and the top of their head. As they fall, rotate their chin to where their forehead was.

I get that you watch a lot of movies, but people don't come at you head tilted back with their throat exposed like the picture you linked.

A perfect liver kick will shutdown the body, a perfect temple hit will black you out, a perfect throat punch will choke you out, a perfect ankle kick will put the feet to sleep, etc. But if your hit relies on perfection, it will miss often.