According to the on-line encyclopedia Wikipedia, no one knows for certain who first uttered this truism. The circus-owner P. T. Barnum may have originated it, since he exhibited fraudulent freaks as part of his circus acts. Besides him, Wikipedia names Michael Cassius McDonald, the nineteenth-century gambling-parlor-boss of Chicago, as the first person to actually say it—or just any swindler looking to get rich quick by bilking poor fools out of their money.

But according to Eric Hoffer, the author of True Believer, a swindler can bilk his victim more easily by offering hope rather than hand-outs—or by offering payback instead of subjugation. It succeeds because you offer the gullible a simplistic way to move forward; and depending on how desperate or angry the gullible person is, the verisimilitude of the pretext will hardly matter. You join the side that promises to move you forward. The prospect of payback excites you more readily than a get-rich-quick scheme.

Depending on how driven, angry, or desperate a gullible man is, he may not get his brain around the possibility of consequences of his actions, that he may experience repercussions for turning violent. He may or may not realize that the huckster who gulled him into this situation has, in effect, led him past the legal threshold, or that the formerly blurred difference between vicitm and perpetrator may turn less blurry and more problematic for him.

Leftists experienced some of that after the Antifa riots, right-wingers after the attack on the Capitol in 2021. I doubt that either side has the humility or the intellectual strength to understand what they have done. In its totality, they play both sides against the middle—against us non-combatants, in other words.

Things might change if the government hired a thousand folk-singers to tour college campuses and sing the Buffalo Springfield's old '60s hit "For What it's Worth":

There's battle-lines being drawn;
Nobody's right if everybody's wrong;
Young people speaking their minds,
Getting so much resistance from behind.

Stop children, what's that sound,
Everybody look what's going down.

Paranoia strikes deep;
Into your heart it will creep;
It starts when you're always afraid;
Step out of line, the men come and take you away.

Also Lionel Trilling, a literature professor at Columbia University published a novel in 1947 about the Alger Hiss Case, titled The Middle of the Journey, about the career of his former classmate at Columbia Whittaker Chambers. Chambers had dropped out of Columbia and  joined the Communist Party in 1925. Finally, he attached himself to a Soviet espionage cell before defecting in 1938. 

Trilling wrote that the Communist Party "had offered the possibility of hoerism or martyrdome, made available the gift of commitment and virtue to those who chose to grasp it."

With the growing realization of Soviet atrocities before and during the War, however, Trilling wrote that "the intellectual power had gone from the system of idealism. . . . The time was getting ripe for a competing system", on that dwelt on guilt and responsibility, spoke of sin and the forgiveness of sin.

We could wait for the guilty parties to come to their senses, but the philosophical war in the United States goes on. It has made us the laughing stock of the World in some quarters. I do not want to wait. We need to divide the Dis-united States and let the warring sides can govern their own nations. Otherwise, we may wait in vain for them to repent.