The answer above is true.
If your son is networking, working very hard and is talented at what he does, he will make it. It's just a really hard row to hoe if you are trying to make a living at anything in the fine arts. I have been in over 40 musical theater productions for both professional theater as well as community theater as an actor or musician in the pit orchestra.
What exactly is it that your son does musically, please?
Concerning publishing a book, if I were to do that, I would want to see if it would be something that is marketable. I would do that by printing off a number of copies and then maybe binding them like some cookbooks are with the ring binders and plastic covers. I would then see if there were any local bookstores that might be willing to put a few copies on the shelves. Putting a book together in such a way would not cost a lot of money.
To my understanding, according to the United States copyright law, anything that you write is automatically copyrighted when you have written it down. So, there is no issue with copyright since what you have written is automatically copyrighted.
You might also want to check out the information on the following sites about publishing a book.
book publishing and self publishing company InstantPublisher.com Simple Book Marketing Tips That Will Make Your Self Published Books Sell Fast