Short answers, pulled from the story.
Greed is defined in psychology as an inordinate desire to acquire or possess more than one needs. The defining feature is an inability to control the reformulation of wants once needs are met, creating insatiable dissatisfaction. Erich Fromm described it as "a bottomless pit which exhausts the person in an endless effort to satisfy the need without ever reaching satisfaction."
Ancient religions consistently condemned greed. The Laws of Manu declared lobha (greed) the root of all immorality. Two of the Ten Commandments in Exodus and Deuteronomy directly prohibit theft and covetousness. The Quran, Christian Gospels, and Persian Zoroastrian tradition each also named avarice as a destructive force. Greek thinkers Plato and Aristotle discussed it as an unjust desire for what belongs to others.
Dante placed the greedy in the fourth circle of Hell in the Inferno, where misers, hoarders, and spendthrifts battle one another eternally. The guide Virgil explains that these souls have lost their individual identities through their disorder and are no longer recognizable. In the Purgatory, avaricious penitents are bound face down on the ground as punishment for concentrating too much on earthly things.
Ivan Boesky was an American financier who, on the 18th of May 1986, told graduates at UC Berkeley's School of Business Administration that greed is healthy and that a person can be greedy and still feel good about themselves. The speech directly inspired the 1987 film Wall Street and its character Gordon Gekko, whose "Greed is good" monologue became one of the most quoted lines in American cinema.
Marx argued that the capitalist is driven by a boundless greed for exchange-value but differs from a miser in method: where the miser hoards money and removes it from circulation, the capitalist constantly throws it back in, seeking not a single profit but the never-ending process of profit-making. Marx called the miser "a capitalist gone mad" and the capitalist "a rational miser."
Some research suggests there may be a genetic component to greedy behavior. Studies indicate that people with a shorter variant of the AVPR1a gene, sometimes called the ruthlessness gene, may behave more selfishly than those with a longer variant. This research is preliminary and does not establish a deterministic link.