Once upon a time there was a cartoon with a happy looking dragon using a lance as a toothpick, and the caption read "Sometimes the Dragon wins..."
No matter how hard you train, how dilligently you practice, how good your habits are, nothing is foolproof.
There are a lot of "what if's" and "what gun is better" and "would a Samurai beat a Gladiator?" sort of discussions. The History Channel has upped the ante with the series "Ultimate Warrior" as if somehow taking humans out of the equation can answer who is the bigger badass.
All men are created equal only in terms of legal representation. This idea flies in the face of "Divine Right", the idea that "I am King because I was born to be King because God ordained it so. To defy me is to defy God". Our American version is simple, that God created with all men to have an equal say in their government.
Men are not created equally in terms of talent, dedication, and environment. Our upbringing, who raises us, is perhaps the most significant factor in determining long term success and survival in our society.
Now that we have these two concepts down, that training doesn't guarantee survival and that men are different, let's get to the point. Being as good as you can be is your best bet at winning. Any trapping of qualification that you earn, whether it is a SEAL trident, Ranger tab, College Diploma, certificate of training from Nacho Pizza Master of Four Weapons, is nothing more than proof that you met minimum requirements.
That is why you can't decide that an Aztec Warrior armed with an obsidian spiked club is a less lethal fighter than a Kung Fu practitioner from the Boxer rebellion. The labels that we put on people are based on some minimum standard, not a maximum. After all, the Professional British "Redcoat" Army had a very hard time against Kentucky irregulars and Afghans alike.
So while it is fun to argue about tactics and training, sometimes the dragon wins. And it is important to recognize that, so we don't train for EVERY scenario, but the most likely ones.
An instructor of mine was asked, "What would you do if somebody snuck up behind you and hit you over the head with a lead pipe?"
His answer was succinct, "Go into a coma and die three days later." Because he knew that having a black belt isn't a guarantee of success or survival.