The claim is about a subjective personal disposition, which is not directly verifiable from public evidence. A 2012 Guardian profile describes Farage as having an "apparently irrepressible optimism," and the interview transcript shows him calling himself "wildly optimistic," but those public characterizations do not objectively establish, on their own, that he was in fact "extremely optimistic" as a measurable fact. Sources: The Guardian, "Nigel Farage: I was never scared of being out on a limb" (https://www.theguardian.com/politics/2012/jul/20/nigel-farage-ukip-leader-interview); High Profiles, "Nigel Farage" (https://highprofiles.info/interview/nigel-farage/).