With so much in stories and history of Hitler, the
Holocaust, The Third Reich, WWII, etc., off and on
for some years I tried to understand what happened
and see if parts of the world or here (in the US)
remain vulnerable to a similar disaster. There
are stacks of history books and many hours of TV. I
boiled it down to:

(1) Authority. At one time, Germany was a battle
ground with the children eating by thawing out
frozen soldiers in the snow. One reaction was
Prussia that became intensely 'militaristic'.
Somehow that Prussian development spread over
Germany and created an 'intensity' and a big respect
for 'authority'. At best there are pros and cons
with that direction, and somehow, on balance,
Germany long went too far.

(2) WWI. That was a disaster. England, France,
Belgium, Germany, Russia, and more suffered.
Finally the US came in and broke the stalemate and
ended it. Yes, the US lost, too. Among all the
suffering, Germany was near the top of the list and,
much of Germany had a hugely bitter reaction.

(3) Versailles. There were 'reparations'. So,
Germany printed money to pay off the reparations
more quickly. Then the inflation ruined the
finances for much of Germany and created more
bitterness.

(4) Democracy. The German efforts at democracy in
the 1920s were clumsy -- more bitterness.

(5) The Great Depression. Sure, the stock market
crash was in the US. So, people had borrowed from
the banks to buy stocks and suddenly had no hope of
paying back. So, the banks went bust. So, the
economy slowed enormously. The 2008 housing crisis
was similar; we did it to ourselves and didn't often
enough see the disaster coming and haven't been very
smart about fixing the problem, and the same song,
first verse was in the 12 years after the 1929
crash. Then somehow the more developed economies
were much more closely linked than one would expect.
So, the US slowed down buying from Germany, and some
Germans lost their jobs; they didn't buy, and more
Germans lost their jobs; they didn't buy from the
US, and more in the US lost their jobs; etc.

(6) Hitler. He was mad, and in particular he was
mad about all the disasters that happened to
Germany. And did I mention, he was mad?
Determined. Ambitious. Ruthless. Can think of
various 'reasons' from his relationship with his
mother, with girls, his struggles in his career, his
WWI experience, etc., but none of these factors has
any 'predictive' power since many others with
similar backgrounds didn't go nuts.

(7) Fertile Ground. Hitler found fertile ground for
organizing and leading, especially leading out of
work, angry, ex-WWI German soldiers. Hitler wanted
to be able to speak and get his followers up on
their hind legs, practiced a lot, and got good at
it.

(8) German Army Politics. The German Army had some
funds for political activities, liked what they saw
in Hitler, and provided just enough 'seed' money to
keep Hitler going in politics.

(9) Communists. In politics it usually can be
helpful to have a visible enemy, and Hitler had the
Communists. And they were also likely a genuine
threat.

(10) Elections. By 1933 or so, Hitler had enough
political followers to start to make some waves in
elections. He didn't do really well, but he did
stay in the game.

(11) Industry. As might be expected, German
industry had some political power. Well, they
thought that Hitler could help them, and Hitler no
doubt was good at playing along. So, eventually
Hindenburg asked Hitler to form a government.

(12) Double Down. Then Hitler and his Nazis were
the government, but they still didn't have much
power. Hitler called for new elections and used the
power he did have to 'stuff the ballot boxes' and do
better in the second election. So, he had more in
the Reichstag, i.e., congress. Then there was some
rough and tumble politics, i.e., before a vote in
the Reichstag some of Hitler's tugs could 'arrange'
that the majority they wanted was present and voting
and the rest were still outside.

(13) Hindenburg Died. Then Hitler got Hindenburg's
job, also, which made Hitler close to a dictator.
E.g., his buddy Goering was head of the police force
in Prussia. Generally his buddies were running
things.

(14) Then, in the words in one of the Star Wars
movies, Hitler pushed through some 'special powers'
for, as I recall, 4 years, to get the economy going
again. Amazingly, he actually did it. So it was
roads, bridges, ships, planes, whatever. The US
should have done as well over the last 4 years. Of
course, it's easier to put people to work when also
have thugs trash the unions and just dictate what
people will get paid -- we don't do such drastic
things in the US. Hitler ran what can be called a
'command economy'. Why most economies run from the
center flop and his didn't, I don't know. But
German industry had reason to be happy with Hitler.

(15) Progress. By 1936 and the Berlin Olympics,
Hitler had Germany looking good, if didn't look too
closely. There was a lot of 'authoritarianism', but
Germany was 'susceptible' to that.

(16) Dictator. Then Hitler got his second term of
special powers, was an absolute dictator, and the
real monster started to come out. "Power corrupts.
Absolute power corrupts absolutely.". Plenty of
people in Germany with good sense saw the threat,
but opposing Hitler was not possible.

(17) Dreams. Hitler had 'dreams'. One of his
dreams was to take over the land to the east,
essentially from Germany to the Arctic, the Urals,
and the Black Sea. He wanted to turn this land into
'farms' owned by Germans and with Slavs as slave
labor on deliberate starvation diets. Everyone else
in that land he wanted just to kill off right away.

So Hitler started making war. E.g., he took half of
Poland and half of France. For war production, he
would turn captured people into slaves.

(18) England. Hitler thought that he could quickly
take England. But before a landing, he had to
defeat the Royal Air Force -- thus started the
Battle of Britain. But Hitler's air force was
really just not up to the job: Both his fighter
planes and his bombers had range too short. Hitler
got angry and tried to bomb London, but his fighters
could not provide protection as far as London, and,
net, in The Battle of Britain Hitler's air force
took unacceptable losses, and Hitler gave up.

(19) Russia. Hitler came close actually to
capturing and holding the lands to the east he had
in mind. But, he got delayed: (A) Stalin was also
running a 'command economy'. So, as Hitler moved
east, Stalin packed up nearly everything of value
and moved it much farther east. (B) As Hitler moved
east, his front grew to be too wide and his supply
lines, too long. (C) Hitler planned badly for the
Russian winter. (D) The Russians regrouped and
pushed back against Hitler and gained time. (E) Due
to events elsewhere, Hitler ran out of time, got
over extended and, basically, was not able actually
to win in Russia. His losses were huge.

Hitler's buddies in Japan declared war on the US, so
so did Hitler, and now he was in a two front war,
with the US, and on a long walk on a short pier.

Hitler was going to take North Africa, move east and
take the Suez Canal and, thus, cut off oil, etc. to
England, and continue to move east and take the
Mideast oil for Germany, but he blew it. First, the
US provided massive supplies to Monty a little west
of Suez. Rommel got pushed back to the west.
England broke the German code, and, thus, much of
Rommel's supplies went to the bottom of the Med. Ike
invaded North Africa, and Rommel went back to
Germany. Hitler's efforts in North Africa were a
bust.

So, Hitler had lost in England, North Africa, and
Russia.

England. The US turned England into an unsinkable
aircraft carrier, and the US Eighth Air Force along
with the Royal Air Force started bombing anything
and everything in Germany. Meanwhile the Russians
were moving west. By D-Day, June 6, 1944, Hitler
was unable to put much of anything into the air.
The Normandy invasion was a great success, in spite
of some cases of hard times, and then it was a fast
charge all the way across France and into Germany.
Germany was getting it from the air, from Russia
from the east, and from the US, England, etc. from
the west.

For the German submarines in the Atlantic, too soon
for Germany the US and England looked at the maps,
blimps, airplanes, radar, sonar, small aircraft
carriers, etc. and from bases in Canada, Greenland,
Iceland, England, etc. had fairly safe passage
across the North Atlantic.

Hitler also had bought heavily into the whole
'eugenics' stuff, Darwin, the image of human
breeding much like dog breeding, etc. and for that
reason, his general resentment and madness, and some
long 'tensions' in Europe, long a very bloody place,
wanted to kill off everyone he regarded as
undesirable. He did a lot, especially in Poland.

It appears that since WWII the main lessons were not
lost on Germany: No more dictators, Nazis, hate
speech, mass unemployment, big inflation, or
militarism. A big social safety net. Work hard and
smart and just do not mess up again.

Could it happen in the US? I'm too afraid it could.
We have to be careful.