Gambling has been mentioned already, but I think it’s also the statistics of gambling that gets lost on people. If something has a 1 in 30 chance of a payout, it doesn’t mean that in 30 tries there will be at least one payout, it means that there is a thirty percent (I don’t know the percentage accuracy right now) chance of that single attempt to payout. When I worked in a liquor store and sold scratch off tickets, people would look at the odds on the back and buy so many thinking this way.