I'm someone familiar with how it works, though obviously I do not search for the material myself - but it depends where one goes. I2P is known for its torrent capability and the torrents can be freely obtained. Tor has various forums that are free to sign up for. Freenet has many, many sites from what I can tell are freesites for this content.

I simply don't buy the idea that the majority of CP advertised on the dark web is only available for pay or exchange; I'm sure a lot of it is, but this "market effect" thing is unsubstantiated as far as I can tell, even though many would like to believe it's a good argument against something heinous, that doesn't mean we should just accept it.

>Plus there's the torment of the victim, knowing that there are people out there to this day jerking off to video of the worst experience of their lives.

This I can understand and actually I regard it as a bigger motivator to the illegalisation of possession. However often they don't know, and could you reassure them that it's not happening if you put an effort toward eradicating only their images? And if they don't know, doesn't that also eradicate this argument in those cases too? What if they don't have a problem with it, or rather, they are neutral about it? The harm would have to be found, and if there is no harm, the argument collapses in that case. Of course the argument also does not apply to pornography in which the victims are dead or unconscious etc. which would seem to, considering only this argument, make such material permissible.