I understand that in some foreign countries staged car accidents for insurance fraud are so common place that dashboard cameras are a necessity. Fortunately, that hasn't caught on in the U.S., at least in this part of the U.S.
The next best reason for a dash cam is to catch a scene for a viral video. Here's one at Liveleak.com that's rather scary. No fraud attempts in this one, just mother nature showing us a little something. No moss on that one. Check it out, it's worth a look.