there are much more than gigging in a musician's life!!!
It's as if you said that doctors only cured the flu!

One of the book's (I've told you) good thing is to tell where music is USED, not played... There are thousands of musicians worldwide that you've never heard about, but you might own or might have heard ten discs/video games/videos/DVD/commercial/radio jingles/telephone rings/ where they play, or have written! Keep that in mind!