Child porn is just ... inexcusable no matter how you think about it. Fine, if some porn stars make themselves look young, okay, but that's consenting adult performers. Abusing Toddlers and children for porn is not just violent in itself, it literally creates wrecks.
Let's not try to justify serious crime, because other crime may be seen as more serious.
Human trafficking, drugs and hitmen services, however, are not - the most notable exception being the various kinds of mafia or other organized crime.
People ruin their lifes, some using drugs. It's true that drugs, like alcohol, may be an existential risk to the life and potential of a small quantity of people. So are casinos, fast food, extreme sports, or videogames.