With the level of frustration and aggravation that spyware brings to the home user, you'd like to imagine that the profits for nefarious folk that create it would be minimal. Unfortunately, it seems quite the opposite. In fact, according to some statistics, the revenues from spyware reach an aggregate of $2 billion. It doesn't take much for a spyware company to run, apparently, and despite the risks it seems to be well worth it:

This explains the vitriol aimed at Direct Revenue. The company, located in a loft above a clothing boutique in New York's hip SoHo district, has been a pioneer in a seamy corner of the booming Net advertising industry. Although it is small by some corporate standards, having generated sales of about $100 million since its start in 2002, its programs have burrowed into nearly 100 million computers and produced billions of pop-up ads.
These companies aren't getting off scot-free. Many of them sooner or later come under the scope of the law and end up defending themselves in court. The article goes into greater deal about the processes these companies employ, though that's largely aside from the point: Spyware is big business and likely is here to stay for a long time.