Those of P. T. Barnum’s acquaintances who mentioned the
subject were unanimous in insisting that he never said this. The
closest thing to it that can be found in Barnum’s writings is:
“I said that the people like to be humbugged when, as in my case,
there is no humbuggery except that which consists in throwing up
sky-rockets and issuing flaming bills and advertisements to attract
public attention to shows which all acknowledge are always clean,
moral, instructive, elevating, and give back to their patrons in
every case several times their money’s worth” (the Bridgeport
Standard, 2 Oct. 1885).

Captain Alexander Williams, a New York City police inspector
at the time, attributed “There’s a sucker born every minute, but
none of them ever die” to Joseph Bessimer, a notorious confidence
trickster of the early 1880s known to the police as “Paper Collar
Joe”. See P. T. Barnum: the Legend and the Man, by A. H. Saxon
(Columbia University Press, 1989).
— From Mark Israel’s “There’s a Sucker Born Every Minute.”