My personal story:
Whitehat:
I work my ass off, make a site with manual content, invest in it to make it really good and useful. All in all about several months of actual work over a timespan of 3 years. Several other sites including cnet.com steal ideas from me and implement on their site. I was ranking 1st page for most keywords. Monetization with Amazon making $1500-3000/mo. Stop doing SEO for about one full year on the site, it stays stable at the top. Then out of the blue I get a -50 penalty and my traffic goes to shit. Obviously I didn't do any bad things since I haven't touched the site in over a year.
Blackhat:
Spend 3 days to code a spam CMS. Get my writer to write spintax ($250 cost). Deploy the thing as an experiment. Forget about it. Re-discover it after half a year, put AdSense on it. Goes from 3000 indexed pages to 20000 indexed pages bc of AdSense bots in a matter of 2 weeks. Because of traffic growth, I'm making about $50/day. Throw some ******** comment spam links to the site from chinese, russian and arab ulra-spammed pages (hundreds or thousands of OBL). After 1 month, I am ranking #1 in google for 20000 keywords. Site now making about $7000/mo. Eventually, links get removed and site drops like a rock. However, during all his lifetime of several months made $35000. I'd say that for 3 days of work and $250 investment it was a decent result
Quote of the day: It's blackhat only if it looks like blackhat to other people.