It is a throwback to the Prosperity Gospel and, before that, the Protestant concept of predestination-- unfortunately prevalent ideas in the early settlers & founders of the US. Basically it says that God favors the faithful & devout with prosperity. Therefore prosperity is a sign of God's favor, and anyone who is not prosperous is therefore immoral/bad/lesser etc. Such things are more complicated than a simple analysis, but it's one of the root causes behind the idea that "poor people are poor by choice"

Perhaps more perniciously, since this doctrine says that the prosperous are those blessed by God, then becoming prosperous is the main goal: the means by which that happens are irrelevant. Cheat/Lie/Con etc., but become prosperous? It must be okay, because the prosperous are blessed by God.