First, let us see why we read.
The one common habit among all the successful people (barring exceptions like Donald Trump) is reading. From Elon Musk to Warren Buffet to Mark Zuckerburg, every successful person highlights the influence they have had from the books that they have read. Because it is the books that we read that shape our world views.
What we read is what inspires us.
Of course, there are two kinds of reading - reading for entertainment and reading for discovering or learning something that we didn't know before. And the books that you can find on the reading lists of all the successful people belong to the latter category. It is not that they don't read books in the humour and thriller genres, but it is just that they don't recommend that others read those.
Entertainment is easily accessible. And different people are entertained by different kinds of stories (and books). So, we are better off asking our siblings and friends for recommendations of entertainers than to ask Mark Zuckerburg for the same.
However, when it comes to books that influence our thought and presents points of view that we haven't considered, we want to read what has inspired the most successful amongst us. Not because reading those helps us in becoming like them. But because it helps us in thinking like them. And that is usually the first step towards doing any meaningful work.
The more ideas we are exposed to, the easier it becomes for us to come up with our own ideas, and to be tolerant of others with ideas that don't match our own.
Ideas are the foundation of tribes.
You flock towards people that think like you. I can bet that the majority of your friends (friends, not acquaintances) are people that understand how you think and have a more or less similar world view. And hence, you are a tribe.
Reading helps us transcend geographical boundaries. My tribe has people from USA, Australia, Europe, India, Brazil and several other disparate countries, simply because we have grown up reading similar things and look at the world in a similar way irrespective of where or what conditions we live in.
Reading is how we connect, and grow, and build.
So, why write?
It is either to entertain or to inspire and spread ideas. Or both.