I've met a few! it is in fact possible to succeed at being a libertarian
(same-sex marriage is the easiest test to make, as it happens. If their opinion is 'duh, of course it should have the same legal status as opposite-sex marriage' you might have found a genuine person who cares about people being free to make choices. If not, you found a garden-variety conservative who thinks small government is a convenient flag to wave)