Well, I don't see it being a function of old time Presbyterianism. I see it as a function of Prosperity Gospel.
Prosperity Gospel teaches that God rewards the righteous with a life without suffering. So if suffering comes your way, well, you must have done something to deserve it. When an impoverished region suddenly has a massive change in its fortunes it is tempted to believe that this is a reward for their virtue. So Prosperity Gospel was Sunbelt Christianity. God is rewarding Bible Belt America.
Prosperity Gospel was intrinsically bound up with the televangelist scandals of the early 80's. It was a corrupt and corrupting doctrine that enabled hucksters to think that getting rich was proof that God approved of whatever they did. I do see that the Christian Right, chastened by that humiliation, has moved sharply against BS artists like Benny Hinn and Robert Tilton and the whole "name it and claim it" racket. Prosperity Gospel begets smug self-satisfaction among the rich which is incredibly Pharisaical.