ROI
Spam persists because of the astonishing return on investment that it generates.
Buy a CD full of e-mail addresses for a tiny amount per addy, splash some cash on some quality time in your favourite Internet cafe, and bring a few pennies for the coffee to drink while watching your mass mailer do it's funky thang, and *BAM* you just sent 100,000 messages. Or more.
If just ONE moron replies / responds / rushes out to buy your product / convinces their girlfriend it will change their private life (delete as applicable) - your time has been gainfully spent. And Deity-of-your-choice knows there are enough morons in the world, daytime TV is proof of that...
Awareness campaigns are all very wonderful, and I appreciate the effort that some people are making to reduce the spammers' incomes... but they'll never eliminate spam, because of this oh-so-tempting ROI. Which is of course even greater when the 'product' concerned doesn't actually exist...
Mines the designer label overcoat that goes so well with this suit...