Is it necessary to always join a coaching to crack any competetive examination ?

In the end, it is your hard work which matters the most. Coaching institutes are just a trend these days. We have many examples where the students have achieved success without any coaching. Self-study is most important.

according to me coaching and self study both are important to crack competitive exams

Coaching institutions for competitive exam not only provide knowledge about the subject matters but also teach techniques of passing the examination successfully such as how to answer in limited time, mock test, review of questions from previous years etc. So many people prefer to join such institutions. However, there are many cases where people have done very well without joining any coaching institutions. They have achieved success through their hard works. So in my opinion, its nt necessary to join coaching institutions to achieve success.

Agree with your view.