Simple answer to why we dislike failure is that we are always result oriented & always have end result in our mind. We always expect a preset outcome for our work. If outcome is to our expectation then we are happy, otherwise, we get disappointed & depressed. It is the nature of our mind only that it gets elated & depressed at the results of our expectations. Say you have appeared for an exam & it's result is to be declared. If you have a preset in your mind that you shall get First class in the exams then you have tuned your mind for an expectation of First class. Now mind shall do it's own work when the result is declared. Just think what, simple, if you do get First class, then your mind shall rejoice & if you don't, it shall get depressed. Problem is not with the mind but with YOU who have programmed it for an expectation. Same is the case with all the work you do in your life with a preset outcome or expectation for your work.
Whenever we are doing a work keeping in mind the end result (say money, promotion etc.) then we tend to live in tension & desperation, driven to "the result" and attached to an outcome. While doing the work in this way takes a toll on our life. We may succeed, we may fail in our goal but in such a case we shall not be doing the work with peaceful mind.
Now see this Philosophy of enjoying the process or life experience while doing any work. Now if you do not work with the end result or preset outcome in mind & rather enjoy the way, the process, the path in doing any work, it shall be much better. Doing any work not keeping the preset end result in mind shall also relieve you from the disappointment of failure. In fact "Life is a journey and not a destination". If we love the journey of doing any work, we shall be more happy & satisfied than if we work with a preset end result in our mind. If we love the journey of doing any work then we shall not be in tension while doing the work. It shall also relieve you of any negative feeling, emotion, embarrassment, regret, etc. in the end if the outcome is negative.
It is the same philosophy that "Bhagwat Gita" teaches us. Here below is the famous quote of Bhagwat Gita:
ma phalesu kadachana
ma karma-phala-hetur bhur
ma te sango ’stv akarmani" (Bhagwat Gita: Chapter Two verse 47)
"Sri Krishna said to Arjuna: You have a right to perform your prescribed duty, but you are not entitled to the fruits of action. Never consider yourself the cause of the results of your activities, and never be attached to not doing your duty."
Basic meaning of this verse is to do your duty and be detached from its outcome. It is only teaching not to be driven by the end product but rather enjoy the process of getting there. The enjoyment of the process, experience of getting there is more important than the end result. It is teaching the same thing, "Life is a journey and not a destination". So enjoy the Journey not only the end result. So it is better to perform your actions and carry out your duty in an efficient way rather than caring or worrying about the results. Below verse also explains more.
"Yoga-sthah kuru karmani
sangam tyaktva dhananjaya
siddhy-asiddhyoh samo bhutva
samatvam yoga ucyate" (Bhagwat Gita: Chapter Two verse 48)
"Sri Krishna said to Arjuna: Perform your duty with an equipoise mind, abandoning all attachment to success or failure. Such equanimity is called Yoga."
Basic meaning of this verse is that if we do our duty or work with equipoise, peaceful mind & do not get attached to success or failure or end result of that endeavor, then we shall do our work effectively. In this way disappointment shall also be not there if we somehow do not succeed in the end. All the philosophy of Bhagwat Gita is only teaching that it is the process, journey of doing work which is important than the end result. Having this attitude of mind, you shall enjoy any activity or situation that you shall come across in your life, without the fear of failure.
Let your life be like a River. River flows with full vigor & power throughout it's journey. So same be your attitude to any work. Do your work with full vigor, enthusiasm & power. Enjoy your work. Doing your work or duty in such a way, your whole life shall be full of joy.
Read also...................................What is Karma?