In reality, most writers can hardly make a living from writing. Their book deals are essentially decided by if the book will sell. For published writers, the biggest factor in publishers' minds is the selling history of her/his previous books. So writers are trying all the means to boost the sale of their books. As far as I know, most writers hate book tours, public readings, etc. They will, however, fly 10 hours to another city, give two readings, each of which may have only 10 people show up, so as to sell several copy of their books, as long as the publishers can cover the travel costs. Most writers are poor and can't afford the travels at their own expense.
So writers really want people to buy their books, not to become rich, simply as a way to support, so that they can afford to write. Writer friends buy each other's books once they are published, as a means to support, both in spirit and in finance. I remember once my family member gave a reading to promote her newly published book. After the reading, a writer friend came to say bye to us, empty-handed. She didn't say anything, but with a very apologetically expression. We know she was having a hard time financially. That expression really hurts.
The financial burden hits hard when writers have family and children. The majority of writers hate teaching, as far as I know. Whenever there is an opening position in a college's writing program, there would be hundreds of applications, including some well-known writers, even although they are aware that teaching will take a big part of their time, their energy from them to work on their own novels, their own books. It seems the cost of context switch between teaching and writing are very high for most writers. A well-known writer, whom I believe most educated people should at least have heard of, can't work on his own books at all when he is teaching. So he has to negotiate with the college to teach only one semester per year, so he can write in the other semester without teaching obligations. I wish his books have higher sale number, so that he can get higher book deals. Thus he doesn't have to teach.