Gambling is a popular global activity. Most studies have focused on risk factors of excessive gambling, including erroneous beliefs related to gambling. Not much is known about why people choose to gamble. The Theory of Reasoned Action proposes that positive attitudes and perceived social norms would predict people’s intention to gamble. The researchers examined the relationship between attitudes and overconfidence in one’s understanding of how outcomes are determined in a game (as a specific form of erroneous belief). They did so in two studies with electronic gaming machines (EGMs) and a new form of gambling, skill-based gaming machines (SGMs). In both studies, participants had a greater overconfidence in how EGMs work. Overconfidence in understanding of how EGMs work was associated with positive attitudes towards EGMs. No such relationship was found for SGMs. These results held after considering important factors such as gambling severity and demographic characteristics.