Many people who want to make a quick buck are seduced by the idea of a free casino. However, there is no such thing as a free casino whether you pay an entrance fee, or pay by your losses, the house advantage employed by all casinos ensures that you will pay back more than you win.
Casinos operate on the principle that gamblers are enticed by the lure of a big win. However, they also set the odds so that losses occur much more frequently than wins. Social gamblers understand this and accept the cost for the sake of the entertainment they get from the gambling experience.
People with gambling problems fail to see the real odds, and instead have distorted perceptions that make them feel that a win, particularly a big win, is more likely than it actually is. This overconfidence is related to the functioning of the brains of people with gambling problems, who are also overconfident in other areas of their lives. This overconfidence makes them vulnerable to great losses, as they fail to perceive the reality of the situation.
Sources
Camchong et al, A Cognitive Neuroscience Approach to Studying the Role of Overconfidence in Problem Gambling. Journal of Gambling Studies 23:185-199. 2007.
Goodie, A. The Role of Perceived Control and Overconfidence in Pathological Gambling. Journal of Gambling Studies 21: 481-502. 2005.

