I tend to believe that child pornography as in literal children is disgusting, but when a girl is around 13 and 14 and looks like she is 20, then theres your reason why people tend to want to see her naked, despite her age, and why older men sleep with women of that age, same goes for women with younger men.
People tend to look at child porn because they enjoy it, it is what arouses them, and they can not get aroused any other way. You will also find people that have been sexually abused when they were younger, and they believe that is what they are supposed to do. Pedophiles themselves believe what they are doing is right, and that society will accept them soon, then you have organizations like NAMBLA, National Association for Man Boy Lovers of America, I believe is there full name. There tend to be many Psychological factors that are involved with people that have a fetish for children, as in young children, pre-teens, and young teenagers.
I myself had a teacher that liked me, she was not my teacher, but taught at the Junior High down the road from my school, and was the teacher of my ex, which is how I met her. She is in her 30's and posed in the Playboy Lingerie magazine I believe from 88-91 or so. However, she is married and has kids now, I met her when I was 17 and we still talk off and on.
Pugz...it is not illegal everywhere, in a lot of European countires there is a young limit, like around 14 or so, when you are able to legally have sex, but sex with children, as in young children tends to be illegal.