The golden age of the fictional villain—twirling his moustache, laughing Frenchly, tying women to train tracks—was the 19th century. In that innocent age, you could actually spook readers with a one-dimensional madman; you didn’t have to bother much with a motivation (unless it was money). But then the modern era came along and started producing real villains with such terrifying efficiency, villains beyond anything we could have imagined or would wish to exist in the world, that crime novelists were forced to respond.
What was a crime really for? What made a person do evil things? Money was still an answer, but there were others, too. Love—passion—the sick, logical, bureaucratic madness of the age. The villains of the hard-boiled genre that emerged in the 1930s and 1940s, in books by Raymond Chandler, Chester Himes, Dashiell Hammett, often combined those reasons, a whole host of contemporary reasons in service of a larger feeling of meaninglessness.