When Adolf Hitler was building up the Nazi movement in the 1920s, leading up to his taking power in the 1930s, he deliberately sought to activate people who did not normally pay much attention to politics.
Such people were a valuable addition to his political base, since they were particularly susceptible to Hitler's rhetoric and had far less basis for questioning his assumptions or his conclusions.
"Useful idiots" was the term supposedly coined by V.I. Lenin to describe similarly unthinking supporters of his dictatorship in the Soviet Union.
Put differently, a democracy needs informed citizens if it is to thrive, or ultimately even survive.
In our times, American democracy is being dismantled, piece by piece, before our very eyes by the current administration in Washington, and few people seem to be concerned about it.
With vastly expanded powers of government available at the discretion of politicians and bureaucrats, private individuals and organizations can be forced into accepting the imposition of powers that were never granted to the government by the Constitution.
If you believe that the end justifies the means, then you don't believe in constitutional government.
And, without constitutional government, freedom cannot endure. There will always be a "crisis" — which, as the president's chief of staff has said, cannot be allowed to "go to waste" as an opportunity to expand the government's power.
Those who cannot see beyond the immediate events to the issues of arbitrary power — vs. the rule of law and the preservation of freedom — are the "useful idiots" of our time. But useful to whom?