Don't sites that ask me to fill out CAPTCHA codes help to proliferate spam? I don't want to be a part of that. Not for a few pennies.
Results of CAPTCHA's being sold to other for various of reasons.
Google gathers a whole lot to make programs to solve signs in pictures, it'll help 'em to make a better Street view.
People that makes ORC programs (or OCR (Don't remember that name)) are buying CAPTCHA information as well. They are doing a very important work, and since I'm not a selfish bugger, I wouldn't dare to not help them...
There are however some who get the CAPTCHA information to make robots that will be able to red CAPTCHA, but it's just some few.
So your statement are to be compared with what I read in a blog:
"... bitcoins serve as opportunities for criminals ..."