I have a friend who has shared her original patterns with 'friends' only to have them teach it in the local quilt shop where she teaches, passing it off as their own design.
Unfortunately, there are folks like that in the world.
Also, when I taught quilting (for money in a shop) I asked them to sign up for the class. It is not fair to those who pay to give it to someone for free. I myself have paid to take a class just so I could get the pattern and then made it at home on my own.
Having said all that ... most people will share. I do share with my quilting 'friends' and would share with anyone on this board, but when I'm planning on selling something (like a handbag or other craft project) I don't really want to give my design to just anyone (locally) so they can make it instead of buying one or even worse, they make it and start selling it in competation with me. This may seem selfish but, frankly, I need the income.
Peggy