They may be selling CDs of expensive people-tracing email sites beloved by stalkers and those into identity theft. Every old con that ever was including snake oil salesmen is going around in spam. Consider the source. Who write the spam to look like it comes from a friend. Who forge headers to make it appear the innocent receiver was the sender.
Spams are scams and senders and willing ISPs are crooks.
Suppose we ignored spam and let the spammers have a clear field to sell their service and post their spam. If just one business in every 10,000 spammed one CD of harvested email addresses a week, email would be a dead service and the internet as we know it would cease. Every mailbox would be blocked to overflow and personal email communication would be impossible by being undeliverable. Internet Service Providers would have all their resources eaten by junk mail, and the internet bandwidth would be flooded and drowned. You and everyone else on-line would spend much of your day deleting spam, and a day or two away from the keyboard would leave you helplessly, hopelessly, inundated.