I tried to put myself into the shoes of the person asking for a copy and just couldn't do it. I have been to places where I see a truly interesting book or pattern someone else has, and would ask to look at it to write down the information about it but could not ever ask to make a copy or even borrow it. That is really over the top. A friend and I will go to the LQS or to a Quilt show and we will each buy separate patterns and then share, but for the most part we don't buy the same patterns because we have different tastes.
I admit I do copy my own books to make quilts because I will put the copied pattern with the quilt I am working on and the book back on the shelf. It is just easier to work with a sheet of paper than a book. And I will copy a pattern too if I need to write on it. Like another member - I was taught not to write in books so even if it is mine, I find it very hard to change.