I've especially resisted putting the large patterns on the market for the past 10 years, because of the "borrowing" and "sharing". With so much "sharing" of patterns, the time and expense to offer them is probably not justified.
Designers, like myself, make our living (pay mortgages, living expenses (like eating), put kids through school, etc.) by whatever talent we may have in creating designs and patterns for those who feel they do not have that same talent or the time or desire to design their own. I draw a pattern because it speaks to me. You buy that pattern because it speaks to you.
So these, without exception, are the rules when purchasing a pattern.
When you buy a pattern you are purchasing the right to use the pattern to make something for yourself or as gifts for family and friends, or to give it as a gift to someone - you could even resell it as long as you don't keep copies for yourself (the same is true when giving it as a gift. You may use it to enter your work in a contest or exhibit as long as your give design credit where credit is due. Credit the designer for the design - you're getting the credit and possible prize money for the choice of colors, placement and workmanship. Good for you!
If you want to use the design to teach a class, have your students buy their own pattern. I always have a teachers discount for 6 or more patterns of the same design, mailed together. That way I make some money and so do you and we both get a new group of quilters excited about quilting...the Hawaiian way.
What you don't buy, when you purchase a pattern or a book of patterns is the right to sell what you make for profit (without permission or royalty payment), "share"the design with someone else, publish the design under your own name, or hand out free patterns (without permission).
Will I or any other designer find out that a pattern has been "shared" or used for profit , probably not. But you'd be surprised that occasionally we DO find out. You're on the honor system. The upshot of all the "sharing"is that the desire to create is diminished, resulting in less designs being offered over time. It is only by selling in volume that designers, like myself, who self publish can afford to continue. So, please to respect our work which you enjoy and to help us protect it so that we may continue to offer you many more splendid books in the years ahead.
Whereas, I know that none of you reading this would ever "share" patterns ;-}, I hope that you will educate others who may.