This issue of Forbes has a fascinating article on how marijuana sales rings are run and how they elude detection and prosecution. The article is very interesting from a social network perspective.
One stat I found quite amazing is:

Most of the marijuana was grown in dozens of private homes across the metropolitan area (including Connecticut and New Jersey), primarily in basements. A typical grower would cultivate 300 to 400 plants, which were harvested up to four times a year, yielding 30 to 40 pounds at each cut, worth $150,000 to $200,000 wholesale.
Wow. I'm not sure how much room 300 marijuana plants … but if you could fit that in your basement and clear $150k/quarter (tax free), that's serious cash. Even if it is only 20% of that, it is still over $100k/year tax free … all for just gardening. (though I imagine the start-up costs (the seeds, special soil, artificial lights, etc.) might be relatively expensive.
I haven't ever seen the show Weeds -- is this what it is about?
My question, if it is really this easy to make over $100k/year tax-free and part-time, why don’t more people do it?
One could argue that it is a testament to our society that people respect the law.
Fascinating…