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).

What could be further form the truth than that?

vince norris