If Irving's story is a satire, what human follies is Irving mocking?

In "The Devil and Tom Walker," Irving uses the character of Tom Walker to mock greed. This is shown clearly through Tom's bargain with the devil, in which he sets himself up as a usurer (moneylender) in return for the treasure.

Tom's greed is immediately obvious to the reader. When the devil suggests that Tom charge two cents per month, for example, Tom says that he will double the rate and charge four. Irving, therefore,...

In "The Devil and Tom Walker," Irving uses the character of Tom Walker to mock greed. This is shown clearly through Tom's bargain with the devil, in which he sets himself up as a usurer (moneylender) in return for the treasure.

Tom's greed is immediately obvious to the reader. When the devil suggests that Tom charge two cents per month, for example, Tom says that he will double the rate and charge four. Irving, therefore, characterizes Tom as being twice as greedy as the devil himself.

In addition, even after becoming a "violent church-goer," Tom's greed never decreases. On the last day of his life, Tom forecloses on a mortgage that will leave a "land jobber" and his family without a home. In this example, Irving mocks Tom's greed through irony.  Tom claims, for example, that he must take care of himself in these "hard times." This is ironic because Tom has no real understanding of hard times. He is one of the richest men in Boston and is not facing abject poverty, like the land jobber.

Greed has become the defining characteristic of Tom Walker and a source of satire for Irving.