Risk-taking in contexts of repeated exposure to monetary gambles is central to human activities such as recreational gambling and financial investing. Evidence suggests that humans tend to take excessive risks in such contexts (“excessive” in an economic sense: not worth the risk, i.e., expected value is negative). Understanding the root cause of this tendency is of pressing concern for a wide range of decision-makers, running the gamut from individual investors, managers of financial institutions, regulators, and recreational gamblers. Anthropology, affective neuroscience, and recent work in neuroeconomics has converged on the idea that someone repeatedly exposed to an uncertain monetary gamble can develop a craving for the monetary reward associated with it, and, once formed, such craving can spillover or generalise to other reward cues. Here we set out to test this idea through controlled experimentation based on a new gambling paradigm.