Lets face the facts, we are all afraid of not being good enough. When we are passionate about something, we often hold high expectations of ourselves when we are involved in it. The fear of not being able to meet our own expectations when following our passion, that drives us to pursue something next to what we are passionate about, and not the subject of passion itself.
To pursue the second best is far easier to digest and less complicated to handle. Since there is not as much respect associated to the subject of pursuit, we can easily excuse ourselves when we fall short, or make mistakes. We often rationalize it with an innate shortcoming, or disability we associate with the subject to the core. It is the inherently lower expectation we have from ourselves when we associate with the second best, that makes the pursuit of the second best so much more lucrative.
Let us look at the our choices of work, or modes of making a living. Most of the people I know who have studied engineering, and doing a faceless job are people who are passionate about something else in life. Be it art, literature, music, sports, etc, their true interest does not lie in their current field of work. They are often dissatisfied with the work, or their performance at it, but they accept it never the less.
One of the major driving force behind this choice is that it is far easier to be a no-one that a someone. We are afraid of not being able to shine if we follow our passion. Most of all, I think what we lack is faith and belief. We are not strong enough to believe that we can be really good at something if we are passionate about it and pursue it at the same time.
Why jobs, we do the same when it comes to relationships. In our lives, we do come across people who we have fantastic connections with, and who seem to understand us completely without a word being said. These are the people who can feel us inside out, and who complete us in ways we never thought possible.
And yet, most of us do not end up with such partners. This often has to do with the fear of unhappiness, of grief, of being hurt. When we are in a average / mediocre relationship, and the basic needs of a relationship such as caring for each other, companionship, sex, etc, it fills a certain piece of the puzzle of standard living. Once we have these basics, and there is nothing more, we look at other avenues for fulfillment, such as work, hobbies, etc.
Another reason why we choose the second best relationship is 'pain'. It works in two ways...you're afraid of getting hurt by the other person, because you have such high expectations from your partner. But above that, you're afraid of hurting your partner because you know what they mean to you, and how much you respect them, and you won't be able to deal with yourself if you inflict pain upon your partner because of your shortcomings or mistakes. This fear leads us to forego the best option, and opt for something less so that we don't have to deal with the fear.
I suppose there is only one way out of this naturally vicious cycle - belief. It is important to believe in ourselves, and our capacity. We cannot be afraid of disappointing the people around us with our choices. But if they are our well wishers, they will soon empathize. Life is all about choices, and we must know that whatever we choose, we're right, as long as we follow our heart.