It could be a teen, posing provocatively, taking a selfie. Maybe they are 17. Maybe they feel the photo will promote a pop star career, or that it could be sold to pay for college. Maybe they just want it for personal reasons, to have 40 years later.
We know that people do this. It's not something that anybody disputes.
Also, hopefully, the police are going heavily after producers and achieving high conviction rates which would give that statistical trend.
That's not true at all.
That said, my understanding is the evidence does seem to indicate a correlation between the two, though in the 30-40% range. See https://web.archive.org/web/20080111204617/http://www.ndaa.o... for example. Not a majority, but still significant. And, of course, this sample is just people who were convicted of possession, not all people who ever viewed such material, so I'd have to qualify my statement to "convicted consumers of child porn"
But there are plenty of people who won't go on to commit a contact offence.
This is a problem for law enforcement because they need to monitor all people who've viewed images of child sexual abuse in order to stop them committing contact offences, and this second group inflates the numbers. Maybe it's only 20% more, but maybe it more than doubles the numbers.
That works only if you pay for said good.
>but images and video do not actually harm any children
Yes, they are. In the creation of that video, a child was harmed. Criminalizing the consumption of a good is aimed at stemming the production of a good.