Why do some individuals make high-risk financial investments? Using millions of linked records from Korea's leading credit bureau, telecom provider, and credit card company, we study the determinants and consequences of speculative activity. We classify explanations for high-risk financial behaviors into two types: those that overcome risk aversion, either through optimistic beliefs or desire for entertainment, and those driven by risk-seeking preferences, endogenously generated from desperation or aspirational motives (à la Friedman and Savage, 1948). Consistent with true risk-seeking motives, crypto app usage is higher among individuals with more unsecured debt, higher spending, and fewer assets, and rises after unemployment and new borrowing. Crypto app usage is also disproportionately concentrated among young and early-middle-aged men. Crypto speculation carries consequences: among crypto users, bitcoin price drops lead to lower consumption and increased delinquency, while a price boom is followed by increases in homeownership. Survey data show that crypto holders are more risk-seeking in choice tasks and more optimistic in their beliefs about crypto returns. In a stylized model, we show that when households are both risk-seeking and overoptimistic, risk-seeking preferences can amplify the negative effects of overoptimism.