Demand does not create a supply.
Supply creates it's own demand.
Say's Law.
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No decent person likes the idea of kiddie porn, but obviously there is a market for it. And where there is a market for it, it will exist. Criminalizing kiddie porn does to it what the war on drugs did for recreational drug use.
You can't stop people from doing things they want to do, and it is very hard to stop people from consuming ideas, media or products into their own bodies if they are bound and determined to do so.
That said, there is nothing inherently wrong at looking at kiddie porn. The crime against the child is not in looking at the porn, but in producing it in the first place (assuming there was not consent).
Attacking the people who want it will just make it more profitable for others to supply it discreetly, which will raise the amount of money in the industry, which will lead people to do even more egregious things to children in order to make a buck.
Think problems out, and really ask yourself if the solution that sounds good emotionally is even capable of yielding a positive result, or if it is possible that the solution might have unintended consequences and make the problem much worse...
Not everything can or should be solved by criminalization. That's sloppy statist thinking.