Why Do You Copy Crochet and Knit Patterns?

My sister and I were having an interesting discussion about copying patterns. She's recently posted on the topic, and I guess a lot of people weren't aware that copying patterns is illegal. I imagine that this is because the practice is so widespread.

I got to wondering why that is, and if having a Netflix-like service for borrowing patterns would help at all. I thought about the reasons why I've copied patterns even when I knew it wasn't kosher, and here were some possible reasons I came up with:

• I don't know when a pattern will come my way again, so I copy it to add it to my file in case I decide I want to make it (although I almost never do make it).
• It's cheaper to copy the pattern than to buy it.
• And if you want to buy it, where would you go to buy it, especially if it's a hard to find or antique pattern and they don't have a website?
• There's a whole book of patterns, 29 of which are hideous and 1 of which is not, and I don't want to buy a whole book.
• My friends want a copy of a pattern I have, so I copy it for them. (This gets back to the first point as well.)

Here's why I think a Netflix-like service for renting patterns would work:

• If I come across a pattern I might like to do later, I can add it to my wish list instead of copying it.
• It would have to be priced cheaper to rent a pattern than to buy it; that's something that would have to be worked out, and it might end up not being cost effective.
• I could borrow the pattern book, make the one pattern I like, and send it back for less than the price of the book.
• I could get a bonus for referring my friends to the service, which would incentivize me to refer my friends instead of making them a copy at my own expense.

My sister is going to put up a poll about it. What do you think? Are there other reasons why people would just copy a pattern? If there was a service like this, would you subscribe? If you subscribed, would you stop copying patterns?