Yes. In general, income that isn't reported and taxed creates a shortfall that honest taxpayers like you and I have to make up. Money skimmed from casinos amounts to hundreds of millions each year. The taxes that aren't paid on those profits must be made up by us. Is it fair that some rich gangster gets richer while workin' stiffs like us pay more?
Don Roberto, you asked how the IRS can know if money's being skimmed:
The IRS has formed a pretty good picture of how much money casinos should be making, based on year-after-year reports and results. They know what the odds are that favor the house, and they keep track of the number of visitors to cities that have casino gambling. If you own a casino in Vegas that has X square feet of gambling space, and that has Y number of slots, tables, etc., then the IRS will have a reasonably accurate idea that you made Z dollars in profits. Of course there's variation in your profits. But if you weren't too greedy in your skim, you'd probably get away with it.
But that's a big "if." Greed by definition is an emotional, not a rational, process. Even if you knew that you could get away with, say, skimming 10 percent of your profits, you'd be sorely tempted to skim more. And that's where you'd get tripped up. Any law enforcement official who's being candid will tell you that crooks are tripped up by their own greed and stupidity, not by ace detective work.