Because...

I once saw this quote in a training institute.
Teach your tongue to say 'I don't know. Then you will learn.  - Confucious

How profound this statement is!

Wisdom comes from ignorance. we are not born wise, except for the genetic instincts. Whatever we know today is a result of our realizing our ignorance and making an effort to learn. if you start with an attitude, 'I know,' then you will learn nothing. You will live and die an ignoramus. It is only by accepting that we don't know something, we will have a chance to learn.

So is the case with all our deficiencies. Don't worry about your deficiencies. The moment you are aware that you lack something is the starting point in your journey to acquire that. So, not having something is not a drawback but an advantage. The realization that you don't have something is a great motivating force. On the other hand denying the truth and deceiving yourself by cultivating a false sense of possession will ensure that you won't develop.

There is a saying: Wisdom comes from experience and experience results from our foolishness. So, you have to be foolish first before you could become wise!

Remember:
I am strong because I have been weak.
I am fearless because I have been afraid.
I am wise because I have been foolish.