Due to the too frequent economic crises,
during my education I considered getting
a Ph.D. in economics. I got some famous
texts on economics, read some chapters,
talked to a famous economics professor,
did a big upchuck, concluded that the
field was hopeless, and stayed with applied
math.

Why hopeless? Here are my guesses:

Data and Reality. Historically the people studying
economies just had far too little data
on their subject. By analogy they were
trying to understand, repair, or re-engineer
a car but had never looked under a car,
never popped the hood, didn't know what
piston rings were, and still were in doubt
if the thing had front wheel or rear wheel
drive. In a medical analogy, they had no
cadavers to dissect, X-rays, MRIs, blood
tests, etc. In an astronomical analogy,
they had no telescopes.

So, they never did well with what is usually
one of the first steps forward for a science
-- the descriptive part where we just give
a good description of the subject.
Astronomy, biology, thermodynamics,
chemistry, electricity and magnetism,
and more all started with good descriptions
of their subjects.

Or, for cars, start tinkering, as Henry
Ford did, with a lot of time with dirty
hands, and only later use finite element
analysis to build models of stress and
strain in continuum mechanics. Or
naval architects had a lot of experience
before they moved to towing tanks and
the Navier-Stokes equations.

Bluntly I had to conclude that the
academic economists really just didn't
have even a first, good descriptive
understanding of a real economy.

During WWII for war production planning,
Leontief worked on 'input-output' models of the
US economy. Good for him. But I was
told that the US academic economics community
very much did not like his work because it
was not 'theoretical' enough as in,
say, 'political economy'. So, it looked
like academic economics wanted to stay with
pomp, pretense, prestige, ignorance,
and incompetence.

One of my Ph.D. advisors wanted me to
take a course in economics so that
if I did any work on a committee on
a 'public sector' problem, then I could defend
myself from attacks by floods of gibberish
from academic economists. I've had
no desire to do any such 'public sector'
work and have not, but I signed up for
the suggested course.

I wanted to be nice to the professor
and not cause trouble. So, during his
lecture with a lot of hand waving and
free hand curves but no data and nothing
convincing, I just took notes and said
nothing. Then after class I asked him
what he was assuming about his curves
-- continuity, uniform continuity,
differentiability, continuous differentiability,
monotonicity, concavity, pseudo-concavity,
quasi-concavity (e.g., in case he was intending
to use constraint qualifications for the
Kuhn-Tucker conditions for optimality).
He was unhappy. Later in the day, I
got a message to see my advisor. I was
out of the economics course -- the professor
claimed that I might disrupt the class.
That was not my intention, but good
riddance! But that professor's reaction
seemed to be a special case of a major
'feature' of academic economics --
have a tightly knit 'club' that
wants only true believers
and pushes out any skeptics. Or
the first rule of Economics Club
is never talk about the rules of
Economics Club!

Net, academic economists know next to
nothing important about any real economy.
Real economic policy needs much more
in data on real economies, insight
into reality, good judgment,
and real effectiveness with applied
math than is common in academic
economics.