I said this elsewhere, so apologies to anyone who thinks I'm repeating myself, but - a lot of people use the word "libertarian" as a way to try to signal that on the one hand they are disengaged from contemporary politics, but on the other hand they have firmly held and deeply thought out political principles (even if they are often unable to describe them beyond 'I'm a libertarian'). I've seen self-proclaimed 'libertarians' argue in favour of some distinctly un-libertarian things. To put it more succinctly, they are trying to signal that they are disengaged but not apathetic - to accrue the social capital that comes from cynicism without losing the social capital that comes from being vague or unprincipled.
'Libertarianism' is a word that has definitely become higher profile in the general public sphere in the last twenty years, but I'm not sure that's due to a renewed faith in libertarian principles, let alone a deeper engagement with libertarian thought. It's mostly just a form of social signalling.
"Anarchist" has a broadly similar function to people on the left, but a longer pedigree.