I've been a weeaboo off-and-on for quite a while and lurked/posted in a lot of spaces, and I can say there are three types of lolicons. I'll make a preface that "2D" refers to drawn content, like 3D would to real-life. This isn't a post about the distinctions between the two or how they relate to the latter.
>The unironic pedophile
Not much to be said here. A coomer that's gone far enough down the 2D rabbit hole that anime-styled underage girls are all that gets him off anymore. Either of the below will frequently be lumped in with this to their protest. This guy (although there are women in all these categories too) will advocate for underage 2D smut as ethical child pornography, ignoring that the porn addiction which led him to this had him progressively breaking new ground on the way. May be or may become an offending pedophile in the 3D world, or may not.
>The ironic lolicon
This annoying type may not masturbate to underage 2D content at all. They will still interact with the content with "playful" jokes like the FBI being on their way in the 4chan party van to arrest anyone else looking at it. A few months ago there was a screencap of a machine translated tweet by a lolicon fan seemingly upset about a girl and how he'd like to give her "rape correction", accompanied by roaring and the crying emoji. This went viral and amused weebs today are still replying with the crying emote and typing "Uoooooh" at lolicon-themed content. This will eventually fade like most memes, but much like gloating that a convicted criminal deserves impending rape in prison, it's objectively vile to see.
>The average weebcel
This can apply to any japanophile who's stuck in porn addiction. The net age for female characters in Japanese comics, cartoons, and games is rather low. Japan has this cultural thing where your life should no longer be interesting when you go to college and enter the workforce, so a most mainstream 2D stories feature teenagers and little kids. By the law of averages, most of the characters designed to be cute or sexy will be underaged in their respective settings. Your average weebcel falls in love or lust with a character, and some of the time that character has a childish body and maybe some accompanying excuse for why it's okay to still lust after her. They can still move away from the brink, but after enough years could develop a kink and then full-on fetish for lolicon.