Imagine with me, for a moment, that you're born with "youth is attractive!" settings set WAY too high. You're growing up, and you reach puberty, and you're attracted to kids. No problem, right? You're young, they're young... it's all good. But you hear about people who are attracted to kids--they're called pedophiles... and EVERYONE HATES THEM. Like... no fucking joke... rabid "I WANT TO MURDERRAPE THEM WITH AIDS INFECTED PITBULLS THAT BARK BEES AT THEM" hate. Hell, you probably even hated on them. Joined in, as it were.

And you keep growing... but your preference for youth never changes. And you come to realize--YOU'RE the monster. You're that thing everyone hates. You hate yourself, too. You're probably in denial. And you can't talk to anyone about it, because you rightly assume that they'll just start trying to stab you to death because "YOU'RE EVAL!!!!1!1!oNE!"

So you try to hide it. From others, and from yourself.

Sex-drive is not something easily ignored, though, and eventually you fall to it. And, in cases such as this guy... you think, "Hey, everyone already thinks I'm Hitler X 2000... why not take out all of this self-hatred and anxiety / stress from hiding on the kids, too?"

Sexual attraction is not something you can decide upon. You can "decide" whether or not to act upon it, but... I don't really think people have as much "free will" and "choice" and "willpower" as everyone seems so desperately to want to believe.

TL;DR Pedophilia is "youth is attractive!" settings being set too high. It's not a choice. Being vengeance-driven psychopath who lives by the "HE DID SOMETHING BAD, SO I GET TO DO SOMETHING WORSE TO HIM, AND BE MORALLY JUSTIFIED!" mentality is untenable. Frothing-at-the-mouth hatred for people who are unlucky enough to be attracted to Those-Who-Cannot-Consent makes them hide rather than seek help, and that makes the issue worse.