Experience and training are highly valuable, having proper tools and preps on hand is a huge advantage. But in the end, without mental toughness and the ability to adapt the most prepared person in the world will still likely bite the dust.

Mental toughness is something that can be taught, to a point. This is the entire purpose of basic training methods used in the military: To take mundane details and elevate them in the minds of trainees while wearing them down with physical punishment. The goal is to condition the mind to ignore distraction, to ignore fear and pain while focusing on the task at hand. Failure is not an option in war, just as it is not an option in survival. Those who embrace distraction and embrace failure because they think it will make things easier for them are filtered out of the recruitment pool, or the gene pool.

It is no coincidence that the US military today is dealing with some of the worst recruitment conditions they have ever seen in terms of people being physically and mentally incapable of finishing basic training. The Pentagon currently estimates that 77% of young Americans are unfit for recruitment without a waiver for obesity, drug use and mental health problems. Meaning, Gen Z is so unfit physically and mentally if there was a major war almost 80% of them would be erased from existence.

The problem has become so bad that militaries in the US and throughout the west are being forced to lower standards just to meet minimum personnel goals. One can argue that many young people don't want to join the military anyway, but this is besides the point. Even if they wanted to, they would not be up to the task.