Why didn't they stop the Nazis in 1933?

I had 4 German-speaking uncles in the American military fighting their firat cousins who had failed to immigrate.

In 12 years, under the cover of much darkness and terror more evil was committed then...
My Dad at age 28, in 1938, (he was a minister, had a smidgen of clout from being just simply shot) exited the Nazi party saying in a letter to them that he thinks they will pursue the harming of the Jewish people and he cannot be part of that.
From then on he was hounded, and had to hide.

Why didn't they stop the Nazis in 1933? It was a matter of life or even more death...plus you had to recognize what was happening, or project what was likely to happen. Not exactly a cake walk in 1933 Germany.

And your saying "failed to immigrate" is loaded as well. Did they recognize the threat and try? Or were they unable to because they were not allowed to by the US? It wasn't that simple.
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Coming to the America of today:
Why don't we stop the people undermining our Democracy?
Who under the guise of wanting less government spending just wasted 24 billion of money in the last 2 and a half weeks that could have fed the children.

an unholy alliance between our corporations & our government, a propaganda-mill mass media that deliberately misinforms the public and turns them against each other, a culture in which science and rationality are despised and denigrated, an exaltation of violence as a universal solution, and a technologically advanced surveillance state backed by militarized police forces that puts to shame anything that might have existed behind the Iron Curtain when it comes to ability to monitor and control the citizenry.

then as now - people actually do have the governments they tolerate (or deserve) until they collapse under their own weight. Some of which has started in the US as heads emerge from the sand slowly but surely.

need to keep poking the sleepwalkers.