What's in it for them?
Yes, but what do bulk e-mailers get out of all this effort? Who is paying for all the work? There must be some return on investment for it to be worthwhile but I don't see where there is enough income when spammers must spend most of their life dodging detection. How do they get paid and who pays them? I'm not only dropping forty or fifty new domain names a day into our spam blocking system, we get a dozens every day to the e-mail address given for engineering inquiries on the company website.
I accept that some spam is straightforward fraud - the real Emperora Bokassa's widow already moved her money out of the country years ago - but does anyone actually buy any of the crap that is advertised in spam?