Barnum.
H. L. Mencken is better known for “Every normal man must be tempted at times to spit on his hands, hoist the black flag, and begin to slit throats.”
Mencken in a column that he wrote.
His actual words were:
“No one in this world, so far as I know — and I have searched the records for years, and employed agents to help me — has ever lost money by underestimating the intelligence of the great masses of the plain people. Nor has anyone ever lost public office thereby.”
Over time, this longer quote came to be paraphrased and misquoted, most commonly in the form “No one ever went broke underestimating the intelligence of the American public.”