I have a question

I understand why the purveyors of spam via viruses/trojans do it: To make money.

I also understand that if a marketing technique remains in use over through many iterations and over a period of several years, that's because it works: Someone, somewhere is making money on the deal.

What I want to know is this:

Who are these people who say to themselves ...

"Some guy wrote a virus that infiltrated my retarded, Outlook-using friend's inbox, extracted my address from it, and sent me a link disguised as deviant porn -- hotnuderedheadwithgreatdane.jpg or whatever -- which, when clicked, leads me to a Mexican pharmacy site. Yes, yes, this is someone I trust to take my credit card number, safeguard it, and in return send me genuine, brand-name, quality-controlled pharmaceuticals at unbelievably low prices."

... ?