Fred Little wrote:
"I will submit to you that every individual who entered into aikido practice, or the practice of any martial art, did so because of fear."
Dammit, this is one of my favorite subjects and, while I agree to a small degree with the "fear" thing, I also disagree with it somewhat.
Many people who go into martial arts go somewhat because of "fear", but for many males, underlying that fear (or even quite apart from any fear) is a desire to be able to compete in the herd for breeding partners. Most of the things we are compelled to do in life can ultimately be attributed to breeding competitions or getting noticed in a way that makes us desireable as a breeding partner. As one stage actor related a conversation he'd had with Sir Lawrence Olivier when he'd wailed, "Oh Larry, why do we do it? Why do we give so much of ourselves for the public?"
Olivier replied, "We do it for 'look at me', 'look at me', 'look at me'."
Many things are done for that reason, including martial arts. It doesn't have to be fear.
Watch the dojo politics sometime and see how much of it can be explained by breeding rituals, including pecking order, etc.
My 2 cents.