When I say "real money" what I mean is that it has become a business with significant cash flows. When things become businesses, whether legitimate or illegitimate, then inevitably you get people who put serious effort into tracking what they are trying and what proved effective. Therefore if they are sending a particular kind of spam a lot it is because that kind of spam has proven to have good enough response rates to justify it.

This effort doesn't mean that spam is profitable. Plenty of businesses work hard, then wind up losing money. But once people invest that much of themselves in what they are doing, they try to improve. And the ones you find still doing it 5 years later generally are doing something right.

By contrast most of the people in Las Vegas are there for entertainment. Pure and simple. They aren't gambling because it works, but instead they are gambling because it is fun.

That said, the parallel isn't entirely inappropriate. There are people who seriously try to make a living gambling. When you look at that pool you find that they put energy into figuring out what works and doing that. Whether they are playing poker, counting cards at blackjack, betting other gamblers that they will lose, or are working for the casino, the professionals quickly learn what works and what doesn't, then try to do a lot more of what works.