The big question in many studies of gambling is the proportion of casino revenues that come from "problem" gamblers: those who are most vulnerable to gambling's addictive side. Problem gamblers make up between 5% to 10% of the gambling population, but contribute disproportionately to casino profit.
A 1999 study by the University of Chicago's National Opinion Research Center (Gerstein et al, here), suggested that the problem-gambler revenue fraction was around 15% (p 34). But this number relied on gamblers' recollection of past losses during phone interviews, and the study itself points out that some of the reported numbers suffered from a "lack of realism". The numbers also mixed casino gambling with lower-stakes lotteries and horse racing.
A detailed study was undertaken by Ontario in 2004 (Williams and Wood, here). In this study, gamblers entered their wins and losses into diaries, completed daily. The conclusion (p 40) was that, on average, 30% of casino table-game revenue came from problem gamblers and a whopping 60% of slot-machine revenue came from problem gamblers.
Little wonder that slot machines are often referred to as the "crack cocaine" of gambling. There is no social interaction to provide restraint. Gamblers sit in front of slot machines for hours, mesmerized.
Data like Ontario's make it clear that problem gamblers are the core source of profit for casinos.
The danger for DeKalb County is that most problem gamblers go to the closest casino. Problem gamblers from the Chicago area are unlikely to drive further than the Hollywood Casino in Aurora. The large majority of problem gamblers at the proposed Shabbona casino will be local residents.
From the beginning, the Prairie Band has firmly insisted on having their casino be open 24 hours a day, every day, for "business" reasons. Illinois commercial casinos are required to close for two hours each day; in 2013 they lobbied to be allowed to remain open 24 hours but the Illinois Gaming Board ultimately voted against this.
The primary way that 24×7 gambling preys on problem gamblers is that it enables "binge" gambling that can last two to three days. Such binges are not infrequent in states that allow 24-hour gambling (several of which border Illinois). 24×7 also means that problem gamblers who win a jackpot close to closing can't "reinvest" it in continued gambling.
"Normal", non-problem gamblers don't gamble at 4:00 am!
There are several proposals to reduce the impact of casinos on problem gamblers. The Prairie Band Potawatomi has agreed to implement none of these!
1. Illinois maintains a "voluntary self-exclusion program". Someone who puts his or her name on this list is not supposed to be allowed into commercial casinos. (Unfortunately, these rules are not always enforced.)
2. Some jurisdictions require that casinos work on a cash-only basis, limiting or not providing ATMs or accepting debit cards (accepting credit cards is supposed to be illegal, but may ATMs give cash advances on credit cards). The goal is to limit losses to the money a gambler came with.
3. It has been proposed, at least, that slot machines should display accurate odds of winning; the elecronic wheels on many machines (intentionally) suggest much better odds than actually exist.
4. Individual slot machines can be configured to shut down after a certain number of hours of play.
5. In Canada some casinos try to identify at-risk gambling behavior in real time; the so-called iGAP system is one approach. The use of loyalty cards makes it easier for casinos to track long-term behavior of individual patrons.