[conservatism_IS_compassion]

PT Barnum had a shorter version. He also paraphrased it with, “A sucker is born every minute.”

It isn’t a lack of intelligence, generally - it is simply that

The natural disposition is always to believe.

It is acquired wisdom and experience only that teach incredulity, and they very seldom teach it enough.

The wisest and most cautious of us all frequently gives credit to stories which he himself is afterwards both ashamed and astonished that he could possibly think of believing. — Adam Smith, Theory of Moral Sentiments (1759)

[Pearls Before Swine]

Whether or not credulity is correlated with intelligence can be debated. The net effect is the same. Many can be molded and led.