vincent p. norris wrote:

Economics is a subset of psychology - psychology applied to
matters of money, assets, liabilities, production, buying
and selling, that sort of thing.


That's not even in the ball park! Have you ever read an economics
text?

The closest economics comes to being "psychological" (and it's about
as "close " as the North Pole is to the South Pole) is in making the
assumption that people always behave "rationally." I.e., that
entrepreneurs maximize profit by equating marginal cost with marginal
revenue and that consumers "equate at the margin" so that the last
penny spent on every good and service provides the same amount of
"utility" (want-satisfaction).

As many economists have long pointed out, those are
safe assumptions. The theory that is derived from the
assumptions accurately predicts how consumers and firms
behave.

All the conclusions of neo-classical price theory can
be derived without introducing "utility" at all. A
professor at UCLA named Armen Alchian, among others,
showed that decades ago. That is, you don't need a
three dimensional map, with goods X and Y on their
respective axes, and utility on a Z axis; you can get
downward sloping demand curves - the fundamental
finding of price theory concerning demand - with only X
and Y axes.


What could be further form the truth than that?

Consumers and firms behave "as if" they knowingly
equate at the margins.