Sorry for the disturbing enquiry but I also wonder...

... besides him being mentally disturbed of course, what caused the lead antagonist character in this movie to have so much scat and other related fetish?

Even if for some reason he managed to get over it being "gross", why was he not worried for instance that he may say choke on it, or develop some strong less than favourable health condition, or even wonder if he could mentally and physically bring himself up to consuming it as if it is ordinary food and why exactly was he into it so much as in, besides what the condition may be, how did he become so drawn into it in this movie at least, why was he not put off physically by its scent and whatnot and even if he was indeed crazy, why fixate himself on this and in that way and how did he manage it all, thanks.