I'm a Google n00b

As an Adobe user group manager, I get 10-20 emails a day from the manager list, folks just chatting. Lately I haven't gotten any. So I checked and they're all in my spam folder.

I was getting so much spam to my google address (really to another address that I have forwarded to google) and one night I was being blasted, 10 spam emails a minute every 7 minutes getting through the spam filters. I checked my inbox to see 147 new messages and 3k spam emails. I must have selected a single email from the manager list while selecting the spam and black listed the address. But I had to shut off mail to the other address. I want to know what the purpose of all this spam is. Is someone really making money off this, or is it done purely to annoy people and stress mail servers?