"The old American Dream ... was the dream of the Puritans, of Benjamin Franklin's "Poor Richard"... of men and women content to accumulate their modest fortunes a little at a time, year by year by year. The new dream was the dream of instant wealth, won in a twinkling by audacity and good luck. [This] golden dream ... became a prominent part of the American psyche only after Sutter's Mill."
https://en.wikipedia.org/wiki/American_Dream?