Wrong. Spam exists because it's easy and cheap to do. Seedy companies sign onto spamming millions. It's very, very easy for me to grab domain names off the net. From there, I use a similiar approach to "dictionary attakcs" on passwords. I have a rather lengthy (and I do mean lengthy) list of "username"@x.com, or .net. or .org. or the country codes. I screw with my headers of the e-mail, and fire off 15 million e-mails across a weekend. Now a days, this is an archaic method. These guys "offshore" their servers, move IP's (networks), hit unwary junior admins and exploit old sendmail and misconfigured mail servers, not to even mention trick local ISP mail servers into cranking out 100's of 1000's of forwarding e-mails.
Try this sometime, make up an obscure e-mail addr at any of the major free webmail services. YOU WILL GET SPAMMED within 48 hours, even if you don't use the account at all. I hate spam for one reason only. It uses resources that it does not technically own...Think about this. You'd be pissed if 100's of vacuum cleaner salesmen were driving up and down your driveway wouldn't you? Well, you should, you are paying for that driveway. It's not theirs.