Depends. There is lolicon that focusses on ages 6 to 10, 10 to 14 and 14+, going from worst to understandable. There are no sexual features to be found in the low age range and I really wonder how people get off to that, but when a young women start to exhibit primary physical features it start it to get understandable. Yeah I've seen it, I might have been on 4chan and imageboards too much. I think it's all related to what you found attractive as a child and not graduating from that due to lack of same-age sexual contact. It's a form of infantilization of the self if you ask me, or hanging on to a something you couldn't get in the past, but I could be wrong.
So to answer your question in multiple parts: pre 14? I have no clue what they are simulating. Maybe just being a fucking bastard that needs to be shot? 14+? Regret and wish fulfillment.
