In The Adventures of Tom Sawyer, how does Tom's view on wealth and treasure differ from reality?

Tom has read enough fiction about pirates and buried treasures that he has some false ideas in his head about how to find treasure. His ideas differ from reality in that he thinks, for instance, that:

You got to find out where the shadow of the limb falls at midnight, and that's where you dig!

This is what he tells Huck, and it comes straight from the fantastic stories he reads. He also informs Huck that treasures are often buried near dead bodies.
More importantly, however, Tom's ideas of what constitute a treasure are limited by his experience. A treasure, to Tom, consists of very little money—even taking into account that a dime and dollar were worth far more than they are today. As the narrator explains:

If his notions of hidden treasure had been analyzed, they would have been found to consist of a handful of real dimes and a bushel of vague, splendid, ungraspable dollars.

As Tom proudly tells Huck that—when and if they find treasure—he will:

buy a new drum, and a sure'nough sword, and a red necktie and a bull pup, and get married.

When he and Huck do discover a treasure worth $12,000, it is more money than Tom can actually imagine possessing.