Dan, I agree - but to say that "everyone's doing it" is crazy. It's easier to trade on material, non-public information if you're exposed to it on a regular basis because your patterns aren't readily apparent.

That said, there are a lot of people who will trade on rumors that they consider "inside information" that things don't work out as well as you'd think they would. Look at the volatility in stocks right before earnings announcements. It's hysterical.